If 10K is your maximum budget...and figuring the computer tasks you mentioned...you might be able to get away with the 2.66ghz "Quad-Core" Mac Pro for $2499, or if you don't mind spending more money...the 2.26ghz 8-core Mac Pro for $3299 would be better.
In either case (for $200 extra)...I would upgrade the graphics card to the Radeon 4870.
If you didn't mind spending some additional money...and you wanted the 8-core Mac Pro...then you could also upgrade the processor speed from 2.26 to 2.66ghz.
So overall...the:
- 2.66ghz Quad-core Mac Pro (with the graphics card upgrade) would cost you $2699.
- 2.26ghz 8-core Mac Pro with the video card upgrade & the 2.66ghz processor upgrade would cost you a total of $4899.
If you need additional ram or hard drive space later on...you can always upgrade that yourself. Apple charges way too much for these upgrades.
Also remember that you can run up to 8 monitors with a Mac Pro...so you could order a Mac Pro with an extra video card as well.
Sorry I didn't spend your whole $10,000 dollar budget!
Hope this helps,
- Nick
p.s. One other thought. If your computing tasks really aren't super super heavy duty...you could always consider a 27" quad-core iMac...and save a bunch of dollars!