for us (well most of us) disk encryption is a big no for games for it takes to much away from the performance. And if you forget your password for the encryption = no more data
If you have a relatively new intel processor and encrypt with AES it really doesn't. Newer intel hardware can natively decrypt AES very quickly. Encrypting your whole drive will add a couple of seconds on to your boot time and the only in game difference will be a fractionally longer loading time as it decrypts the necessary files before dumping them in to memory. MMO's and elder scrolls games would take the biggest performance hit, but even then not by much.
Also on the general topic: (Warning, this is a bit of a braindump and is probably not in any logical order.)
You can never be completely secure. It isn't possible.
Use long, complex passwords. Write them down in pen on a piece of paper. Put them in an $80 officeworks safe that is bolted to the floor of your house. For "Security questions" make up a random string of letters, numbers and characters, write them down, and put them in the safe. Never use answers to security questions that are even remotely related to the question you pick.
"But how do I come up with a good, long password that I can remember?"
Here is an easy way. Pick 2 obscure songs that you like but nobody else knows you like. Pick a line from each song. Mash the words together, change some of the letters to numbers and add a couple of random special characters somewhere. You should now have a 30+ character password that will be ridiculously difficult to bruteforce and somewhat easy to remember for you and only you.
If you want the tinfoil hat approach: Get a dirt cheap computer, like an rPi or something for under $50. Put linux on it. Encrypt it. Firewall it. Lock it down. (If its an rPi put it in the safe!

)This is now your financial computer. Everything that you ever do that involves money is done on this machine. It is only connected to the internet when you need it to be. Nothing else is ever done on this computer. Ever.
Separate your "Serious business" internet life and your "Herp derp internet user" life. Use an email address and passsword set solely for your forums accounts and WoW subscriptions. Have no connection between your life on the internet where you troll youtube comments and your life on the internet where you manage your banking.
I should take far more of my own advice.