and i onley got $200 to spent on my computer what should i get in video and MB RAM

is it just my video card because i goint to up graed it and add a littel bet more MB RAM and why dos NVIDIA GeForce4 MX 4000 dos not supported it

i got a dell dimension 8300 it has pentium 4 Hyperthreader 3.0Ghz 512MB RAM a NVIDIA GeForce4 MX 4000 128MB shuld the game be abele to work on it ??? and it Windows XP home p2