hi..

I am using windows xp 4 GB ram and athlon xp 1.9 processor dual core but my computer is gets slowed down randomly every few seconds and then get normal but it is occurring so fast that my computer is unusable. It slows down for 2-4 seconds then works for 10 seconds then again goes.. I checked for virus and downloaded antimalware and there is no CPU spikes but still it is slows.

Is it due to virus or some other problem ?How can I fix this .. plz help...

This is because your Graphics card or CPU is overheating.

AMD is using intelligent clock-back to Slow down the CPU clock to prevent it from Burning.
Check for dust inside your PC.

It may be possible that heatsink is dislodged or Dust has damaged the fan.

It happens more with laptops, as heatsinks are very small

wait till end of this month windows7 will be launched by that time so go for7

actually if you are using vista it slows down after sometime but same is not true for windowsxp and seven.
Windows7 is more stable and don't give errors as in xp moreover as it is latest OS of microsoft so it contains all the drivers(updated).

yeah if u do fresh installation your lappi will reagian its orignal speed.