Need recommendation for Mid-High End workstation/gaming system

Hi,

The last system I build started getting a little flaky - I've been trying to re-install Vista Ultimate 64-bit for the last 24 hours without much success. As soon as it installs and I try to load the latest Geforce drivers, the whole system crashes. I'm running the Windows Memory Diagnostics tool overnight in Extended test mode to see if there's a bad module.

I'm a computer consultant, and I do a lot of computer programming, running virtual machines at times, and then gaming when time permits. My typical process is to take my old workstations and turn them into file/application servers for my development.

The last system is roughly this:
Tyan S2895 Mobo
Dual Opteron 280 CPUs
4GB ram
4 500GB SATA3 RAID 0+1
Dual NVIDIA 7900 GTX (512MB)

I ran this with dual boot for XP Pro (tried 64 bit, but not enough driver support to stayed with 32 bit) and Vista Ultimate 64 bit. It's been a great workstation

I don't have time to fiddle without my main workstation, so I'm thinking it's time to replace this with a new machine and as I have time I'll convert this to still a rather nice app/file server. I probably still want Vista Ultimate 64 bit and XP Pro. I run dual displays at 1900x1200 resolution. Besides programming in .Net and Java, and running Oracle and/or SQL Server, I like to play Flight Sim X, Supreme Commander, Lord of the Rings Online, and other such games at 1900x1200. I've contemplated the video cards that are dual GPUs integrated into 1 slot, but I'm thinking that will not be as efficient if dual PCI-E slots have better bandwidth these days. I was assuming a quad-core CPU or two, but I've also seen posts that say you can get better performance with dual core.

Based on this info, what would you recommend? I need at least 4 SATA ports for Raid 0+1, and additional ones might be nice to have a drive for automated backups!

Thank you!

--Kent

Is there a budget?