Building a New Computer

[AntiochusIII]

...and I quite ashamedly am admitting that I've been out of the world of hardware for far too long. Therefore I'm coming for some help.

The Goal:
-A machine that can play Oblivion smoothly, quite beautifully, as best as I can get on a limited budget. If Oblivion can run, everything else I've wanted to do should be fine.
-A stable machine. I'm willing to reduce performance a teeny little bit if it would save me from, or at least reduce the instances of, the headaches I'm having with every computer of mine since antiquity.

The Limitations:
-A desktop, not of any brands. They suck.
-A budget of around 1000$USD. Yes, it is low and hard to work with, that's why I'm coming for help. I might be able to stretch over a bit but then I'll have to pay for Windows XP, too, and somebody to build the computer for me.

The Points:
-I want an AMD. It's a rule when it comes to gaming.
-I want an Nvidia for various reasons, personal, prejudice, and otherwise. The best I could fine as long as it is proportionately balanced (so to speak) with the rest of my computer.
-I'll need a DVD-drive, at least. Perhaps CD-writer too. If somehow I can also write DVD, it'll be nice, but that's the least of priorities.
-The monitor doesn't have to be perfect. It can even be the big, fat, old-fashioned style. I don't care. It just have to be at least 17' and stable/nice.
-About 1-2GB Ram, depending on what I can spare. It should be balanced, of course, with the rest. But the minimum I'm looking for is 1GB, whatever form or shape.
-A good mainboard. This is the least extent of my knowledge: the sockets confuse the hell out of me.
-A soundcard that more knowledgable orgahs say are good for gaming, but I personally don't really see much difference. So it's behind in priorities. Oh, and a decent speaker, I suppose. I'm looking into Creative Labs ones.
-A good HD of about 160 or 200GB. Not necessarily the biggest or fastest, I want the most stable; my current one's a mess.
-Lotsa quiet fans, I suppose. To make it stable.
-A good case.
-And all the rest that doesn't really matter like a floppy disk, etc. Which doesn't count.

Advices, please, and they will be most appreciated by this humble ignoramus.