While at a local pawn shop I seen a Dell Vistro 200 there selling for $237 abd some change. Below are the spec that I copyed down and later looked up on the net that matches what I saw
Specs:
Intel® Celeron® Processor 420 (1.60GHz, 800FSB)
1GB Dual Channel DDR2 SDRAM 667MHz - 2DIMMs
80GB Serial ATA Hard Drive (7200RPM) w/DataBurst Cache™
Single Drive: 48x CD-RW / DVD-ROM Combo Drive
Intel® Graphics Media Accelerator 3100

Is something like this worth the money to get and would it be able to run games (*nothing all that major like WarHammer or such*), I want to give it to my roommate so he can have something to mess around with.
Also how easy / hard is it to self upgrade Dell products, I've been told in the past that Dells were designed and made in a way that users cant (*any truth to that?*)

It all depends on the slots and the case. I would say for a basic pc this is ok. You should be able to upgrade the proc with something similar in clock speed and that uses the same socket number ie switch to pentium d1.6ghz. You could replace drives and would have to see what the max ram is for the machine. I know from past experiences that swapping anafter market board in a dell if possible usually takes some reconfiguration of the case. I have had to use a dremmel, jb weld, and epoxy to do this for someone that wanted the same case but an updated board. You may want to check craigslist for a cheap pc also. I have flipped a number of pc's here that I have bought reloaded cleaned up upgraded with a few small parts and sold for a profit.

Play games on it? Sure. Modern games? Probably not in any resolution / graphic quality that you'd want to. I'm not sure what the system requirements are on WarHammer, but I'm gonna go with no on that too. There are a number of older games that would run great on it... Age of Empires 2, UT, Counter Strike, etc... all still fun to play, and cheap if not free to acquire.

The main problem with that system is going to be the fact that it probably doesn't have any PCI-E slots to drop a new vid card in. Thus, you're stuck with integrated video, which blows. Also, the processor is poopy.