i got an xecuter 2 in mine you can probably get that for $50 and that works fine.the xecuter 3 is the latest one i know off but that will set you back $60-$100 depending on where you get it.shop around and you might find a bargain.
I've never used an Xecuter so I have nothing to compare to, but I would like to say that Xenium is pretty good. Mine was about $50 (would have been a little cheaper but I got the solderless adapter). I have had no problems with it; it was easy to install and use. The only downside I could find with it is that there is little documentation for it compared to Xecuter chips. It also came with an external light kit and usb adapter (so you can use a usb keyboard or mouse).
1 more question..what do i have to do to be able to get a new hd to work on the xbox (taking out my tertiary from my comp...160 gigs)
putting a hard drive in can be alot of work. 1.install the modchip 2.flash or upgrade the bios 3.use autoinstaller such as slayers once you put the new drive in using slayer or any auto.installer should do most the work for you