Deciding On A Graphics Card

I currently have a Hewlett-Packard CQ60 Notebook PC. It has:

2.00 gigahertz AMD Athlon Dual-Core QL-62
64 kilobyte primary memory cache
1024 kilobyte secondary memory cache

Slimtype DVD A DS8A2L-A ATA Device

250.06 Gigabytes Usable Hard Drive Capacity

2 GB DDR2 Memory

Board: Wistron 303C 08.48
Bus Clock: 133 megahertz
BIOS: Hewlett-Packard F.33

Windows Vista Home Premium

NVIDIA GeForce 8200M G [Display adapter]
Generic PnP Monitor

I am looking to upgrade my graphics card, I can barely play games like Red Alert, it plays Red Alert without lag only if it is on low graphic setting. It probably won't work at all if I try and play Left 4 Dead or Fallout. I don't know much about compatibility, but I was looking at the Galaxy GeForce 9800 GT Video Card - 512MB DDR3, PCI Express 2.0, SLI Ready, (Dual Link) Dual DVI, HDTV at Tigerdirect for 84.99 after rebate. From what I have seen it seems to be a pretty good price. I want to game and watch HD videos on my PC, what graphics card should I buy? I was also looking to upgrade my memory to 3 OR 4GB, is it worth to upgrade. Thanks.