PSU = Dead?

I booted up my computer and was greeted with a nice loud grinding sound. The sound eventually died down to barely tolerable, but I still am worried. At first I thought I had to backup everything on my hard drive and that the apocalypse was nigh, but it turns out that the fan on my power supply unit was making the obnoxious noise. This is sort of a bad time because I was about to do something crazy on my computer.
EDIT: It appears it is now harmless. My older (and much smarter) brother, Matt (who gave me this computer in the first place) says that the fan likely has sand in it and he would come out and fix it. :)
I just bought Half-Life 2. So, what's the deal? In case you couldn't tell from my previous post, the computer was all I could afford (a grand total of 0$). Here are the specs:

412MB of ram
Nvidia Geforce2 MX Graphics Card (64mb, no pixel shaders)
Like, 10gb of free space on my 80gig hard drive
450mhz Pentium III processor
Windows XP Professional SP2


As you can tell, I am probably going to get 10fps if I am lucky. I got about 20 fps on World of Warcraft, about half the graphics detail of Half Life. There are actually lots of console commands in Half Life (none in WoW for obvious reasons; cheating if you are dumb or computer challenged) that control various aspects of the game and rendering. I assume I can turn off the pixel shaders and reflectivity so that the computer at least doesn't explode. (Just sizzle a little bit and set fire to my house). My biggest concern is not the graphics but the physics. With my puny, weak-minded CPU, I cannot load too many physics objects, but I have to if I want to play half life. Now to attempt to install this game (I heard it is notorious for long, cumbersome installations). So, now all I have to do is install the game and seal the fate of teh computer forevar. Yes, it's worth it. Yes, I am partially insane.