Ok guys so this is the situation, i own, right now, a toshiba satelite laptop, but recently i have tried Rift and i REALLY like it, so here are the specs of my new extreme budget build, also i do not need a CD drive or HDD or operating system.
Look at the $500 build in my sig. That's got a HD5770, Athlon II X3 455 and costs $340 without OS, DVD and HDD. Much better than what you have picked. You can probably even upgrade the processor to a X4 955BE and still stay within budget.