I would think that these parts would do just fine for $3000 bucks. I am assuming that you will OC a little bit and you already have a monitor, speakers, keyboard, and mouse. If you don't, PM me and I could help you.
Case: Thermaltake Kandalf
It costs $189. Should have enough room for anything you plan on putting into your computer. I think it would do fine for water cooling as well. I am going to assume you want air cooling.
Power Supply:Silverstone Zeus 650 Watt SLI PSU
It costs $169.99. Everyone likes the PC Power and Cooling 510 Watt SLI Supply. IMO, it is overkill AND loud. This will do just fine. It has quad +12V rails. You wont need any more power.
Processor: AMD X2 4800+
The best processor, along with the FX-57, on the market right now. It is dual core with both cores running at 2.4Ghz. That does NOT mean the speed is 4.8Ghz total. It just means you can multitask a LOT more with this processor. It costs $787.00, not too cheap
Heatsink: Zalman CNPS9500
You are going to need a good heatsink to cool you CPU; it is essential especially for overclocking. Zalman makes the best heatsinks on the market. It costs $57.99.
Motherboard:DFI Lanparty SLI-DR
DFI is the preferred company with any AMD processors with almost everyone. This board is an extremely good overclocker but it is a little picky with the ram. It is usually not a beginner board, but you should be fine if you ask people here
. Costs $189.00. Asus also has a A8N32 motherboard, which features 2 x16 slots. I don't know about the performance gain you get with this over this motherboard. Maybe someone else here can help you out.
Memory: OCZ Gold 2GB PC3200 Memory
1GB used to be enough but that's not the case anymore. 2GB will soon become a must. Already, some games like BF2 use up almost all of the 2 gigs of the ram. Trust me, you are going to need it. It costs $275.44 after a $30 rebate
Hard Drives: Western Digital Caviar 300GB Hard Drive
Since you have the money and are willing to spend it, get two of these. One is only $115.00, practically a steal at that price. Two should give you 600GB of space, you can expand later if you want. Costs $230.00 for both of them.
Video Card: eVGA 7800GTX 512mb
This card comes out tommorow and should be the fastest on the market for a while. The downside is the price, somewhere around $650
. On the upside, you won't need to upgrade for a while. It should destroy the X1800XT but you should check the benchmarks tommorow or in a few days to be sure.
Sound Card: X-Fi Xtrememusic
Audigy just replaced their ZS line with the X-Fis, their new flagship models. These are something like 50 times more powerful than the ZS versions, some number..i don't remember off the top of my head. "Only" costs $117.50
Optical Drive: NEC DVD Burner
Its a DVD burner, they are all the same so no point paying a lot for one. This one is nice and cheap at $38.99.
OS: Microsoft XP Pro
It's Microsoft. It's Windows. Enough said. Costs $154.95.
That should cover everything. The total comes out to $2858.86, assuming I didn't forget anything
. You might need some for shipping
. BUT you could shop at ZipZoomFly, free shipping on everything except for the case. You could cut down on some stuff like the hard drive in particular, but hey you have the money