Hi, I want to upgrade my computer for gaming like left 4 dead 2. I have a Compaq Presario sr1650nx (HP Compaq Presario SR1650NX (Athlon 64 3500+ 2.2GHz, 1GB RAM, 250GB HDD, XP Media Center 2005) specs and Desktop specifications - CNET Reviews)) and my motherboard is a Asus A8AE-LE (Motherboard Specifications, A8AE-LE (AmberineM) Compaq Presario SR1650NX Desktop PC - HP Customer Care (United States - English))). I kind of want to upgrade the motherboard/processor, the graphics card, and the power supply but I don't have that high of a budget like $300, maybe $400. So I need suggestions on what to do about upgrading?