Had the same problem with just XP, no MCE on my HP. Had my first talk with CC today and they told me that there is no way to upgrade to MCE from XPHome - it has to be total BIOS install from factory.... He mentioned something about "swapping" to another. Needed to head back home and do another total system search to be sure MCE wasn't anywhere to be found (it wasn't). Will be heading back in soon to find out what the "swap" offer is.
Hmm, and I was disappointed that there was no second drive in second bay...