Problem with Computer slow speed

[abhipal]

My config:
Intel P4 2.8GHz (64bit), Intel D101GGC with onboard gfx card x200 with 256MB can be shared from RAM, 1 GB single chip RAM (think 400 MHz), Windows media center, Kaspersky Internet Security.

My Problem:
When I format my PC and install fresh windows it runs with good speed for 5 to 10 days but after that it starts to slow down. And my friends PC which is P4 2.4 (not with HT) runs faster than my PC. How come? Does it have anything to do with the hour usages. On an average my PC stays on for 15 to 18 hrs in straight.
Please help me guys coz it's really a pain to watch your PC slowing down.

[napster007]

first and formost get tune up utilities man!! will definately show results.

[s18000rpm]

1- Defragment the Drives
2- run CCleaner to delete temp. unwanted files.
3- when browsing gets slow- delete IE7's [or whichever browser u use] cache.
4- lastly whenever you install/uninstall apps., move/delete/copy files, run a good registry cleaner (like TuneUp Utilities 2007 [paid])

[Choto Cheeta]

I wounder too many people running Windows XP MCE in their assembled PC ... How Come ?? There is no OEM version of Windows XP MCE !!!

or is there any and I am missing the point ??

[s18000rpm]

Pirated copies have soooo many problems

my XP Home (HP), never had problems like @abhipal's, i didnt know anything about "Temp." files, registry... 2 years ago ,even so, my PC was as quick as it was when new. (Norton quick, that is )

[DeSmOnD dAvId]

-Check for viruses
-Scan your PC with HijackThis!
-Follow the steps shown by others above.

BTW, did you assemble that PC of yours? If so, it seems like you have got a pirated version of Windows XP MCE.