yea that is a shame for a hd 4830 as if overclocked it was on par with the 4850,
i was going to get a 4830 but ended up getting a 96gt, seems to be powerful enough to run all games at 12x10 on my 21" crt monitor. my next card will most likely be a gts250 when prices drop or s/hand one will do
your next best upgrade should really be a cpu as the pentium 4's really suffer in newer games, you could maybe bang a cheap core2 or pentium dualy in your rig and will notice quite a difference, steer clear of the new celerons though as there pooper scoop. all depends on your mobo though.