Hi, I'm currently running Windows XP 32-bit. I play games such as Counterstrike Source and TF2.
I'm looking to buy a new laptop, and the one I'm looking to get comes with Windows 7 64-bit.
Do I need to worry about these games having compatibility issues or anything like that running on a 64-bit OS?
Short version - do you need to worry? No.
Longer version - Windows 64bit can quite happily run any 32bit program (n.b. the same isn't true for drivers), so any game that runs on Windows XP will run on Windows 7 64-bit. The only exceptions are games designed to run on XP only (rather than XP or above) but you'd know as these wouldn't work on Vista either, and games that have a 16bit installer as 64bit cannot run 16bit at all. This basically means the only games that won't run on 64bit are REALLY old ones that came out pre-XP or very early XP. Best idea is to google for your favourite games as if they won't run on 64bit it will definitely show up on page 1 with lots of annoyed forum posts. The two games you've listed I haven't personally got, but I would be amazed if either has a problem.