Unless you intend on going with 5+ monitors later on, I'd stay with two 2 port cards for a 4 monitor setup. If one card fails, you can still have 2 monitors left, etc. Also less than 1/3 cost to replace compared to a 4 port card.
No plan to go +5 monitors. But I'd be sure that the card (or cards) would work. I'd have no use of the 2-port cards (like 285 and 290) if they do not work in my setup. I already have two identical ATI PCIe cards (dual port ATI X1xxx series). So I won't have any backup issue. When I upgrade to a newer mainboard, I may be able to set up the ATI cards to drive 4 monitors also.
Sounds like you're going to either take a risk on which cards will work in Vista, like buy 290/285 on eBay... 2 cards for $60-$80, total, or buy an expensive quad x16 card. You could get the NVS 290/285 cards on eBay and try them out. If they don't work (which they should), sell them again. Worst that would happen is that you be out abut $20. Or, you can pop for $400 for a new quad... might get a used 440 for $200 or so...
Before giving up on 2 2 port cards, I'd play around with them some more. I've seen installations, for example, where the *order* of which video card/software is installed 1st, determines whether everything will work. Little things in the installation process sometimes make all the difference. You'd be surprised.
I think I'll get a either a nVidia 400 or Matrox G450. So I should not have imcompatibility issue unless the driver sucks. But XP and Vista have been good with older video cards. when I upgrade to i5/i7 system, I'd plug in my dual ATI PCIe cards. I hope they will work. If not, I can still use the quad PCI I'm going to buy now. I may get the quad PCIe if I see the need. Thanks for the help. I just do not have the time to try different dual-video cards.
Just ordered a Matrox G450 card. It won over the nVidia 400 with the 128 MB RAM, instead of the 64MB RAM. Both decent prices. It is supported by both Vista x86 and x64. This will keep me going for quite some time. I see the next upgrade to i5/i7 is at least 1 year or 2. By that time, most of the mainboards would have two PCIe x16 slots and I'll have more options. Thanks for the help. The folks here are nice and knowledgeable!
Your 19" monitors... are they widescreens and are you running them on DVI? If "yes", you really should have chosen the Quadro NVS 440 instead... you're probably not going to like your Matrox G450MMS... You're OK, however, if you plan to run 4, 19", conventionals... 1280x1024 resolution.
if all else fails, you can always try the usb adapter. i don't have any problems using it for trading.