Are you building it or buying a pre-built from dell or hp or something?
if it's only for work, video card does not matter, it's stupid when people try to say "well i hear the dx10 cards are WAY better for graphic design than the older cards". It has nothing to do with graphics, only thing it would have anything to do with is the way the colors are displayed on the monitor, and even then they're all about the same. The only designing that a gfx card would have anything to do with would be 3d rendering, using d3d or opengl. Neither of which ps, ai etc etc have anything to do with.
Now with having that said. Your best bet on a system would be based around an intel core 2 duo, preferably 2.2ghz and faster. The cheapest core 2 quattro just dropped to 300 dollars, that is what I would go with. Get a 965express chipset (they just released a new intel chipset, haven't read much about it, but I do believe the boards start around 200 dollars). I would say get two harddrives, so you can have one as your boot and one as a scratch disk/backup drive. Maybe 1 150 gig raptor for boot and a 500 gig sataII for storage and whatever. Most drives are SATAII now, so there shouldn't be a problem there, i would imagine all 965 boards have sataII ports onboard. As for ram, most ddr2 800 will be fine. Windows xp 32 bit can only allocate 3.5 gigs maximum, 64 bit can allocate a LOT more than that, so if you want to go 4 gigs of ram you will have to use 64 bit xp, core2duo's do run xp 64bit. Don't buy vista, chances are your versacamm or your plotter won't work. I have heard problems about versaworks and vista. Anything else feel free to ask.