I'd just like to add that I don't think it's necessary to buy a dual/quad video card unless there is an issue with available space in your computer. I currently have 4 19" CRTs, each running on a separate but identical card. I have Win2k Pro but have had 3 monitors on Win98 in the past. I've never used the dual/quad cards so I don't know if they're better. All I know is I've had no problems with my setup and it's much cheaper!
BTW, I must suggest as others have that you get Win2k. Having used both Win98 & Win2k for trading and on multi-monitor set-ups, I STRONGLY RECOMMEND WIN2K!! However I got Win2k pre-installed when I bought a new computer. I understand there may be issues trying to upgrade from Win98.
Just my 2 cents,
Tony