I highly DOUBT compaq blocks you to just Windows, they aren't Dell, they don't worship MS.
I was talking about PnP settings and a few other settings in BIOS' designed for Windows, I've never personally had a problem with them (however I have seen WinXP machines running with BIOS' config'd like it was 1994, so my point was that maybe Ubuntu doesn't <3 that (not just the date, i'm talking about like FDD configurations, drive layout, etc))
Idk, it was a shot in the dark, i'd try clearing the CMOS just for the hell of it, finally, I'd really like to know HOW Compaq would block all OS' except MS Windows, without A) breaking the DMCA/anti-trust/anti-competitive laws B) pissing off a huge ass ammt of people C) having it super documented D) WHY?! and also i don't even have a clue as to how you'd go about locking a system thusly...
EDIT
just an idea, I have no actual basis for this though, I know ATI's graphics drivers + linux = crap, that system uses an ATI chipset, and ATI's chipsets suck even worse than their gfx adapters do (seriously, their chipsets are nothing amazing, at all) so maybe it's the chipset sucking it up/being incompatable (like I say, I have nothing to really base this on, don't own an ATI based mobo (thank god))
EDIT 2
ok after looking at ubuntu's website, that's some bullshit, they don't list system requirements/supported hardware ANYWHERE, and they're full of f'ing shit if they wanna say it supports every piece of hardware EVER MADE, Gentoo doesn't list any chipset support req's
HERE:
http://www.ati.com/products/radeonxpress200Intel/specs.htmlATI claims it has "support for Linux operating systems"
which in my opinion is about like saying a guy has "support for intercourse" that doesn't really give you much, beyond that it COULD work
so, i'm guessing it might be your wonderful canadian brand chipset, or it might be the motherboard not being entirely supported, can't gurantee either, and i'm not in the mood to dig out my old HP P4 board and test out my theory...except it uses the 815, which should work fine...