I've got a similar problem - XP taking 3+ minutes to boot on a 2.4Ghz Celeron w/ 512RAM. Startup loads sophos auto updater, zone alarm, and broadband connection software. So nothing much. The laptop was fitted with a new HD in October, but is otherwise 3 1/2 years old.
Oh, and I get a message saying my mousepad drivers are not synaptics approved, even though I've rolled them back to factory settings. Is there anyway to get rid of this?