Maybe you could provide us with some more information, like, is there any instance the computer just "waits" for several seconds. For example:
1. The computer waits while setting up the network connections -> network issue.
2. The computer (hard drive) works (almost) all the time, but it's painfully slow -> possibly a hdd issue. Check that DMA is enabled, and download
this fix or the whole
new SP2. Also, do a disk benchmark if have one (like
Sisoft Sandra drive benchmark).
3. The computer "freezes" after the start menu appears: this is due to many programs that start automatically. Try disabling them one by one to see if anyone of them takes "far too much" resources. For example, virus scanner.
4. Check this excellent KT7(a) guide:
Paul's KT7 faq!
Good luck!