Even for non linux-enthusiastic users, replacing linux by windows on this offer cant be a choice based on a technical and unbiased decision.
First, the hardware (i will assume the intel site is updated and match this offer) :
"DDR-II 256M SO-DIMM"
Last time i tryed to use windows XP with 256mb ram, it wasn't exactly fast... Add any word processor on the top of it, and you can be sure scrolling on a reasonably small document with images will be a very frustrating XPeriance. With linux on a reasonably light window manager, it run just fine.
Then, the software... Mandriva can come packaged with all the program a student need, and with easy "system + program" update mechanisms, while upgrading applications on windows require at least manual install (if picking freesoftware on the top of windows) or more money.
Upgrading the OS : how does Nigeria plan to move to the more recent versions of microsoft windows when XP will be unsupported ? It's a 2001 operating system, and every new MS-OS double the hardware requirements. The failure of vista will mitigate the "end of life" timing of XP, but that's just for a time until microsoft can "persuade more people that Vista is good for them".
I can understand mandriva guys to be disoriented by this biased fight. Could Nigeria consider dual booting... Or is more important for ballmer to delete linux than to install windows ?