Found this info:
MINIMUM REQUIREMENTS:
Windows Vista or Windows XP
Processor2.4+ GHz Intel; 2.0+ Ghz AMD
RAM 1GB
Hard Drive12 GB free hard drive space
Video CardNVIDIA GeForce 6600+, ATI X700+
Online Multi-player:Broadband Internet Connection, Games for Windows -- LIVE
Your specs, including actual computer Ram, look to be too low
You may need another gig of Ram as well (ie the above is minimum)