Windows MCE is just a software program installed on windowsxp home like sage or beyond is so the answer is a definate yes.
The only difference is that mce is a program that is installed with the os like ie or outlook or any other MS bundled software. The big difference is the drivers that come with MCE cards are designed to work with only the MCE software ( I'll let you speculate yourself as to why that is) so i believe you need a regular xp driver to make it work without mce. From what i have read and heard the pvr 500 is just 2 pvr 150 mce's on one pci card so from what i've read you should be able to get it working the same way by installing the regular pvre 150 non mce drivers off of Hauppauge's or SHS's site.
Their should still be on some filesharing programs a downloadable beta of the original mce that works in any windows xp system if your inclined to look at it (I did shortly after it came out but didn't like it really it wasn't all that different from the free myhtpc program that someone else i can't recall ( sorry i have some crappy short term memory for names and numbers) put out.
Anyway if your hesitant just wait till one of the other people who have ordered it from this
thread get theirs and try it out and see how well it works or doesn't for them.
Oh yes and happy turkey day don't forget to
a bird for dinner