Can't replace my slow hardrive

I wouldn't used SSD for gaming which it seemed like what you want right?

Why the WD slowing down your PC? it could be that you don't have enough MEMORY (a good option to upgrade for Vista user). or Buy a new case and start retooling from scratch.

SSD are kind of pricey and they are mostly for servers. a WD velociraptor will be fine. but whats wrong with your current HDD?

take a dremel tool and cut the screw off or drill it out with a drill
be careful take your time and tape/block off the area so the metal shavings dont get on the motherboard.

alternatively remove everything from case then do it.

if you dont care about data loss, just snag 2 seagate 7200.12 500GB drives or similar and run it in a raid 0.

thats about 100$ solution.
I'd hold off on SSD for now as they are going to be getting much cheaper/better

and they arent big enough by themselves to be the only drive in computer.

Heck, for the price difference in even one of those drives, you could buy a really expensive new case! Spend $100 on a 1TB WD Caviar Black and $100 on a new case and you're still under the cost of a 320GB Velociraptor.

And the WD Black is fast and quiet - with gobs of space.

And send me that crappy old 320GB WD! It wouldn't be slow in my system. All it likely needs is a fresh format and install of Windows.

What kind of vibration you got there? I haven't had a hard drive fail in 10 yrs - and never screw them in. And you can always look for an old computer case and get a drive cage from it - this one's from an old Compaq.

"Stripped screw" should not stop you.

IF the problem is that the screw threads or the threads in the sheet metal are damaged so the screw won't hold, that can be solved by using a different, slightly larger self-tapping screw to replace it. However, getting the old one out requires a bit of work. Now, if the slot in the screw head (often a "+" shape Philips) is OK you can turn the screw, but maybe it won't actually come out - just turns! In that case you need to slide something thin under the screw head - a small screwdriver blade, or a thin knife blade - and use that with a gentle twisting motion WHILE YOU TURN THE SCREW so that the screw has a force to pull it out of the hole. On the other hand, if the screw head's slot is damaged and you can't turn it with a normal screwdriver, try to grab its head with a pair of pliers - a small Vise-Grip (locking plier) tool is great for this - and turn it out that way. If neither of these works, drilling it out with attention to avoiding flying metal chips is the last resort.

Once the screw is out, just find another self-tapping screw to replace it that will actually do the job. It will have to be a larger diameter than the one you removed, and you should make sure it's not too long, but it's not hard to make the substitution.