I placed two orders with bmmods.com and was extremely happy with both. Order 58 was a complete system overhaul including a 200 GB hdd, mod chip install and an increased volume case fan. Order 84 was for a latter version x.PSU for a friend's box (that was hit by lightning).
The installer was prompt with email and IM replies, always helpful before, during and after the transaction. He answered any and all of my questions quickly and concisely. My completed machine (58) was returned to me within 7 days, and has worked flawlessly for several weeks. I am extremely happy with the transaction. While the bmmods.com prices are on the high side, I gladly paid more for quality parts and peace of mind.
The only caveats of the orders was that the stock hdd returned to me (since the 200gb was installed) had not been unlocked, so I will have to put it back in the xbox to unlock it and be able to use it in one of my older computers. This negated one of my reasons for using bmmods, so I wouldn't have to mess around with the internals of the xbox. Also, due to legal reasons, the installer could not put the mod chip bios nor an updated dashboard on the box ... which was a mild inconvenience as I had to do several hours of online research to get caught up enough so I wouldn't destroy my now pricey game console system.
I anticipate using this installer in the future for any of my xbox modification needs.