Huh? No "other" version of DX9? How about DX9, DX9a, DX9b, or even DX9c?
Forgot those, huh?
I'll have to agree about the Emachine though. Every Emachine I've ever worked on was throw away PC. Sounds like your processor is actually a Celeron D 3.33mhz. If that's the case, yeah, you most likely have PCI/e. However, Emachines are extremely sensitive when it comes to replacing or upgrading ANYTHING. For one, most have proprietary powersupplies of the lowest possible quality and adding anything to them, even memory, will blow the powersupply. If you add a better videocard, you will most definitely fry the PSU (powersupply). Most good video cards require alteast 350 watts of CONTINUOUS output, not an occasional surge to 350 watts. PSU stats are VERY misleading. I find the advertisements that sell 650watt PSUs for $29.99 quite amusing, but feel sorry for the poor guy who falls for it.
Also, if I may ask.......Why on earth would you EVER buy an eMachine???