They have a kit for sale on ebay that replaces the x-clamps that hold the heatsinks on the gpu and cpu. I've used the kit numerous times of many different xboxes (friends paied me to do it) and none of them have gotten the rrod since. If you're not afraid to open up your xbox and do all the work (there is a very good guide included with the kits) you can have your xbox up and running in about an 90 minutes (thats about how long it took me my first time, but I've cut that in half after doing it for about 6 different people). Here's a link to the kit:
The seller has many different kits available, but this is the one I use since I already have a t8 and t10 torx screwdriver. Other than that all you need is a small flathead screwdriver to open the xbox (there is a special tool that makes it a lot easier but it's not worth paying for IMO). Once you buy the kit the guy will email you with a link to his extensive guides for opening and repairing the xbox.
Tip: Use 90%+ isopropyl alcohol to clean off the old thermal compound (works just as well as their cleaning solution offered in their other kits). I use a coffee filter to rub it off (no lint and still somewhat absorbant). Taking the old, dried up thermal compound off is the most time consuming. Also, I highly recommend using Arctic Silver as opposed to the thermal compound they include (the stuff they give you works fine but it's not as good as AS5).
If you have any additional questions feel free to ask me.
Note: This kit isn't a guaranteed fix, as it only provides better contact between the cpu/gpu and their heatsinks but in most cases this fix lasts a long time (years). A solder re-flow is the best way to fix it but you will have to send it in to somebody who will want a pretty penny to fix it. This is the best DIY fix.