Need help building a new rig! (with budget)

Ok I’ve never done this before, but I want to build my own PC (with help from some IT friends) and I need to figure out a build for a gaming PC. I’d like it to be less than $800, but able to play a game like Lord of the Rings Online on Ultra-High graphics as seamlessly as possible. Here are the recommended requirements:

O.S.: Windows® XP/Vista
Processor: Intel Pentium® 4 2.8 GHz or equivalent
RAM: 1GB
Video: 128MB NVIDIA GeForce® 6800 or ATI® Radeon® X850
Disk Space: 10GB available
DirectX: DirectX® 9.0c
Optical Drive: 2X DVD ROM
Connection: Broadband DSL/Cable

Links to each item would be great, if possible. I also need a new monitor, but that doesn’t have to be in the $800. If you can fit it in, more power to you.

Good luck, I know I’m in good hands!