Advice needed: How to build a gaming PC!

Ok, i need help. Please pass on this posting to your geek-inclined friends, if you know any. :) I'm a semi-geek myself (used to be a full-time geek), so i know one of the best geek-pleasures is giving out geek-advice. *LOL*

I'm planning to buy a new custom built gaming desktop system. Have been out of the industry for so long, i don't know what's the best and the brightest hardware anymore.

Have roughly RM2k to spend, don't need a monitor, or CD drive.

Based on current prices and available products in the market, what should i buy?

Key Questions:

1. What's the difference between AMD and Pentium, as far as gaming goes?

2. ATI or NVIDIA?

Comments and shopping lists are very much appreciated! Thanks.