First some basics. If the sites you use have some method of two-step verification options, such as a password plus a SecurID token, use it.

You should also get in the habit of changing your password on a regular basis. Once a month is good, once a week is better. You can keep your password written down and stored securely in a safe.

It should go without saying but I'm going to say it anyway. Never use the remember my password feature. 

You check a monster on the river with thousands of dollars already in the pot, expecting your opponent to bet the river. He bets and you're about to hit raise when all of a sudden your connection drops out. Or maybe you're short stacked in an MTT and just got dealt aces when you're about to cold 4 bet and ... connecting...

When you finally do connect you're on massive monkey tilt and shoving any two cards. It's fairly simple to make your internet connection more reliable.

If you depend on the internet to make money you should have at least two broadband internet connections. Preferably from two different carriers. This is easy to do in most markets as you can get a combination of cable and FiOS or DSL. 

Using a special router like this TP-LINK TL-R470T+ allows you to have two broadband connections attached to your home/office network. If one of them goes down hopefully the other is still alive.

In addition you'll want to keep all your networking hardware attached to an uninterruptible power supply (UPS) to keep them running for at least a little while if you experience a power failure. One of the APC Back-UPS is a good choice for networking hardware. It's like a surge protector with a built in battery that helps protect the equipment from power issues and provides back up battery power in the event of a power outage. These are great for little hiccups in power or short outages but are best used as a temporary step before your backup generator kicks in for extended power loss.

Virtual Networks

You're going to be using your internet connection for a host of other things besides poker. Almost everything is connected these days from your phones to TVs to your garage door opener. It's possible to create separate private networks within your home network to help keep your poker computers secure. That way if your buddy comes over and wants to check his email with his laptop or phone he can do it but not have access to the computers you use to play poker. You'll need a smart switch that is VLAN capable. Something like the Cisco SG200-08 8-port Gigabit Smart Switch.  

Create one VLAN for your regular internet usage and have a WiFi access point attached to that it. Another VLAN will be for your pokering and you'll set it up so that they can both access the internet but they can't talk to each other.

Redundant Hard Drives

I think you're better off having a desktop as your main poker computer. More reliable, more powerful. Hard drives and hard drive controllers can and do fail. You can set up two drives in a mirror (RAID 0) where all data is written to both at the same time. That way if one fails the other keeps going until you replace the failed drive. It also increases read performance.

An ideal setup would be to install an additional PCI SATA controller in your computer so you have two. One from the motherboard, one from the card. Use 2 SSD drives for the best performance and set them up as mirrored drives through software. I've been using the OCZ Vertex SSDs on different systems and very happy with them.

Install the drives in a mobile rack. The ICY DOCK ToughArmor MB994SP-4S Mobile Rack is a good choice and very durable. It makes it easy to swap out drives if they fail but more importantly allows you to easily remove the drives for storage.

When you're done playing poker, pull the drives out and put them in your safe until the next time you are playing poker. If you want to use the same desktop for other computing you can have a different set of drives for that. Keep your poker rig for poker only. Don't install IM, Skype, or other software that's not related to poker. Don't even browse the web or check email. Keep a laptop nearby that's on your "public" VLAN for that.

You'll also want a separate UPS for your desktop and monitors. Get the biggest one you can afford for the most run time.

Back Up

On a regular basis, like maybe at the end of each session or at least each week, back up your computer data to an external drive and keep it in a safe place. Even though the RAID setup provides you with some security it's not a substitute for backups.

I have a Rosewill RX-DU300 Black Hard Drive Dock which I use for backups. I like it because I can buy regular desktop hard drives that pop right into it instead of more expensive external drives.

Remember to keep your backup drives secure too.

It's important to have a laptop in addition to your desktop. In case everything fails on your desktop you can always resume play on your laptop. If you're a high stakes player you can afford to get a laptop that's just for playing poker. No email, no Skype, no web browsing. Just something you keep at the ready in case you need it. You should have a safe that's big enough to fit your laptop in addition to your SSDs.

Sometimes you'll want to be able to play while traveling. My best advice, every time your computer leaves your safe little poker network treat it as if it needs to be quarantined.

Before you head out for a trip backup your laptop's hard drive. When you return don't boot it up normally. Instead insert a CD that contains your backup software that boots up into it's own environment or use a Linux distribution like SystemRescueCD. Use that to restore the drive data you backed up before you left. That way your laptop is exactly the same as it was before your trip and any nasty software it might have picked up along the way is erased. 

Once the drive is restored, run a full virus scan before booting it up just to be safe. You can use the AVG Rescue CD for that.

The on drawback is that you'll lose any data you might have added to your computer while you were away but these day's that isn't a big deal. Use cloud services like Google Drive to take notes and store files or use your phone. It's much better than finding out your hotel room was broken into and your laptop hacked.

Sometimes people's systems get compromised because they don't know what to do but a lot of the times even when people know what to do they get lax and don't do it. If the money you have in your poker accounts is important to you then take a few simple steps to minimize the risks.