The x-box gamertag list should show ya who has a 360, if none of em replies drop one a PM. My brother though asked the same question, only advice I could give him was don't get the core one, spend that little extra for the HDD, wireless controller, the HDD alone makes it worth the extra.
Impossible to really compare to the other next gen consoles though as PS3 and Wii not been out long, and PS3 won't be out here till middle of next year and probably not really available till the end (and costs more than the other 2 put together) and Wii I'd guess won't be freely available until early/middle next year and has it's "funky" motion sensing controller which you will be able to try in person in some stores from end of the year or in one of the Nintendo tours going on soon in the UK/Ireland. Powerwise though if that's your thing it's Wii at the bottom (focusing more on price, gameplay and aiming for wider market with it's Wii-mote controller), then 360 (best on-line play I'd say), then PS3 (best graphics/power, highest cost of machine and games though)