New Computer - Need suggestions on hardware

[Mar-Evayave]

Hey guys, I'm working on getting a new computer. My itty-bitty Dell laptop that is half a decade old at least is starting to attack games like a wet noodle. Time to retire the gecko and get me a dragon.

Okay, maybe not that much of a beast, but still...

Here are my current specs (the laptop):

Dell Precision M65
Windows XP Pro SP3 32-bit
DirectX 9.0c
Intel Core 2 Duo CPU @ 2.00GHz
2 GB of RAM
NVidia Quadro FX 350M
CDRW/DVD
150 GB harddrive

Can't think of anything else off the top of my head, except that most of my graphic settings are low to medium, with a few high/very high settings. In a happy world, my FPS is 20-30. In higher level areas or those with lots of people (RoR, HD, Epic Battles, raids, etc) my FPS drops to 10-20 or even lower. I manage, but it's not exactly fun. Oh, and when HD first launched, I'd crash about once every 30-60 minutes. Sometimes more often. Same story with RoR. Can't remember much further back, though I vaguely recall similar experiences with RoI. Anyway, as with RoI and RoR, give the game a little while and things like crashes and even the worst of rubberbanding gradually deminishes. RoI is peachy, RoR is pretty solid, and HD is getting better.

Now, my new system is not all together. Only have a few things. It is a desktop, though.

Dell Optiplex 745
No operating system yet (shooting for Windows 7 64-bit)
DirectX 9.0c is more or less a given
Intel Pentium D CPU @ 3.40GHz
305 watt power supply
No RAM yet (shooting for 4GB, but considering 8)
No video card yet (this I really need help on)
CDRW/DVD
No harddrive yet (shooting for a TB)

I'm pretty certain I'll get the above operating system and harddrive, and will definitely get at least 4 GB if not 8 GB of RAM. What I really don't know is what video card to go with. I'm not 100% sure how to find out what would be compatible. All I know in terms of the nitty-gritty details on the processor/motherboard is that the entire thing is SATA and the video card slot is PCIE x16.

Anything else I need to share or is this enough to get the ball rolling?

I did some minor pricing on crucial and newegg and it seems like I can get a TB harddrive for about $60-$70. 4 GB of RAM runs about the same, though I did see one bundle of 8 GB for $110 or so. When it comes to the video card, I really don't need (or even want) the top of the line. My budget for just the video card runs up to about $150, so I'm looking in that range. I don't need to have a super computer. xD