well you can try the above mentioned
but i would like suggest to either increase your C drive partition size.
if not possible try upgrading.
as 5GB for OS is good till windows 98SE, you need to try atleast 10 gb for windows XP if you need to install a few good programs with it.
and if you apply service pack to it it will go beyond 2.4 gb+ (just windowsXP and Servicepack 2) add office to it 550MB+, see what you need is bit large partition.
system restore feature will eats up plenty of your presious space. dissable it.
from time to time empty your temp folder (use cleantemp for this free one and erase your temp folder contents every time you boot), empty the cache of the browser you uses (they have this feature which empty the cache when you close the browser).
do not empty prefetch folder too often as it will decrease your system performance
though i would not suggest to dissable hibernation as for its feature but if you do not use this dissable it to from control panel's power option.
shift the paging file to some other drive of your hdd (if you have space on them) other than your C drive