Display-only card advice

I’m making a new modern Linux box for myself, should be fun… haven’t built a PC for a couple years.
I’m planning to mostly follow the suggestions of Tech Report’s workstation guide: http://techreport.com/articles.x/16721/8 though with an Antec P183 case, and no sound card, and different video cards.

This will give me an i7 box with 12GB of RAM and spacing to run multiple cards.
The motherboard is an Asus P6T which isn’t ideal but should be fine.

Now comes the CUDA part, I have a lot of fun options. I am thinking that I will install three diverse boards:
A 295GTX for raw crunch power, a Quadro 4800 for >1GB RAM testing, and maybe an oldschool 9800GTX+ for a third board.
The 9800 is so I can use it for display while the Big Boys crunch. It will also let me test some device 1.1 behavior as well.

The motherboard has two x16 and one x8 slot with double-wide spacing so I should be able to squeeze them all in there OK.

My question… is it unreasonable to try to support three diverse cards in one box in Linux? Will I have trouble with selecting which one is for display, or with drivers which get confused
since they all have different specs? I plan to use Unbuntu 9.04 though I could change that too I guess.

Should I give up on the “lowend display” card idea? I’d love to be able to develop without fear of lockups by keeping display away from the high horsepower cards.

Just FYI: There are now consumer cards with > 1 GB of RAM.

GTX 275 w/ 1768 MB: $309

GTX 285 w/ 2 GB: $409

Thanks, I noticed that myself! That’s pretty cool to be honest.

I already have the Quadro though, I plan to move it from one of my older Windows boxes.