Single Status Update
I decided to give Linux a fair chance, since I got a new system (Dell Inspiron 1720 laptop). I opted for the latest Ubuntu 9.0.4, 64 bit edition.
Other than creating a bit of a mess with the partitions (Dell laptops have some weird extra partitions), LILO/GRUB installed just fine on the MBR and allowed me to boot normally to XP, but fucked up the MediaDirect partition (essentially an embedded XP provided by Dell). Not much of a loss here, I read that the correct approach was to manually override the default installation of grub/lilo on the MBR and place it somewhere else...
Other than than, it surprisingly worked quite well, even with my WPA-secured wireless connection (I've had a bad experience on my desktop system, with a non-functional "blob" driver for a PCI-e Wi-Fi adapter).
It fucks up somewhat on shutdown, though.
In any case, I guess it doesn't hurt to have an extra functional OS along to complement the other. We'll see how it fares on the long term.