I should go ahead and mention here about Saints Row 2:
The PC version is considered essentially the worst PC port ever done. To start, it has speed issues related to OS for both Vista and 7 (it apparently just doesn't run on XP, not really a surprise). I guess the farther your processor speed is from 3.2GHz (the 360 processor speed), regardless of if it's higher or lower, the faster the game moves. There are tools to fix this, which I'll mention in a moment.
As well, the game crashes. A lot. I guess the auto-save absolutely can not be trusted, so even with fixes, you should save pretty much every time you do anything that you don't want to redo, such as completing a mission, buying goods, etc. That means saving in separate slots as well. You need a lot of saves to play the game start to finish. Patches or not, this always applies. Nothing short of recoding the game yourself to iron out the metric fuck ton of freezing and crashing bugs will make saving a non-issue.
I read something about the game managing to completely skip the step of prefetching as well, and although my technical expertise is fairly limited, from what I understand, it's pretty much a stupid miracle that the developer managed to keep the game from doing this. If this actually ends up being a problem for you, the simple solution is to delete the general prefetch file the computer has likely been keeping since you first launched an application on your computer (you can find the exact file path with a Google), restart your machine, and start up Saints Row 2 first. This seems to actually make the game prefetch, for whatever the reason might be. It's a pretty simple solution, and I guess it works for near everybody.
On top of all of this, even if you get the game running half decently, you will still run into a couple freezing issues after certain missions and cut scenes.
Lucky for everybody, modders have released a pretty comprehensive patch that both adds content and does bug fixes. The Gentleman of the Row mod, which you can find with a quick Google quite easily, is a patch that both fixes freezes, some crashing issues and the speed issues on Windows 7, as well as adding content that makes the game feel like a more complete and fun experience. I installed this mod and started up the game without the notorious first time launch crashing, and made it through part of the tutorial before giving up on my helplessly crappy laptop in regards to running the game on half decent settings smoothly. It should be noted that some slowdown may just occur because, well, the port is a really shitty port. There are a few fixes, which I'll leave more for the source of all of this info. By no means will the game ever be anywhere near a perfect experience, but this helps it to be somewhat passable for the $1 to $5 most of you spent.
To read more comprehensive info, get exact links, and learn what other things you may need to do to get the game running, check out this absolutely fantastic FAQ from the Steam community forums that I got all of this information from:
http://forums.steampowered.com/forums/showthread.php?t=1715922