A jump of that size for the hard drive will slow down any boot/shutdown time
if not properly handled. You should consider partitioning the drive, AT LEAST
into 2 smaller partitions (2 100GB partitions) or, better yet, partition a
small section of the drive ONLY for windows. Set aside about 10-20GB that you
will only use to install windows, Windows updates, and other necessary
drivers and information. Then have a separate partition for data and/or
program files. This greatly inproves load and boot time, especially on IDE
based systems without a RAID array.
Also, if it is sluggish getting into windows itself after the Windows XP
screen, try running MSconfig (start-run-msconfig) and go to the startup tab
and remove any programs from running at startup that you might not need (just
be careful not remove any vital things. Only remove things that are necessary
and that you recognize. Anything else don't touch until you research what it
is.)