XP's boot cycle is mostly fixed. The conditional elements are the
3rd-Party services and startups that run immediately after Boot
and System drivers load. Most times the optional components
start to load around 37 seconds into the boot cycle. You can do
a little trimming of Startup & Watchdogs ( Printer monitors....) that
appear in the System Tray to shorten boot up a little. Otherwise
it's mostly dependant on your installed applications and services
and there's not much an average user can do to reduce their effects
on the boot cycle time.
Last time I checked my machine it finishes loading at 57 seconds
from a cold start boot. That includes a minimized Media Player &
six 3rd-party applications/services such as Zone Alarm, Nod32.
It might help if you posted your current boot time to help determine
if it's an "Out-of-the-Ordinary" situation or normal for most XP
setups.