Here is an existing writeup here but i was going to make my own. Oh well. Oh and I have the parts list from home depot so you don't have to buy their kit. Also you don't need the xbox "opening tool". A precision screwdriver works fine.
http://llamma.com/xbox360/repair/ring_of_light_x-clamp_fix.htm
Here are the official home depot part numbers:
Qty - 8 Machine Screw Pan - Phillips 5 x 10mm (DR# - 313) UPC - 030699 801282
Qty - 16 Flat Washer Nylon #10 (DR# - 610) UPC - 030699 869381
Qty - 16 Flat Washer Steel / ZINC Plated 5mm (DR# - 606) UPC - 030699 363087
Do NOT use the 'hex' head screws as an alternative, they are too large and cause your motherboard to bend when you screw it all back together.
Note: The 'DR#' is the 'drawer number' and may not be the same at every home depot. I've visited 3 now with the same drawer numbers, but the upc and description is the best way to find it. If you still can't find it go find an older male worker. They can usually find the screws almost immediately