i just installed vista on a new pc, but when i fully install it, it says that im missing files or i have insuffisint sources to start halo 2. Y is this happening.

Here are my pc specs

Intel Pentium Dual Core Proceesor Inside 1.66 ghz

1013 mb of ram

226 mb of video memory

320 gb hdd

intel (R) 82945G Express Chipset Family

Windows Vista Home Premium