fully agree with psdavinci,
def have to have 7 or newer, i also used to have 5..like 98 i think lol
but 5 is lacking free transform tools,liquify tool (awesome for smoothing out wheel wells etc...just turn down the brush density and brush pressure below 20) some tools also.
cs3 is the bomb and most people at my work prefer cs2( apparently does not lag as much,but i havent seen it)
just get it legally so you can register it,you can benefit from lots of offers from adobe.
bet you could find 7 or 8 for a pretty cheap price online
it son