Will an overheated cpu recover?

I was burning a DVD recently on a hot summer evening. The pc case doesn't have any cooling fans, there's just the one over the P4 478 3GHz cpu.

It got hot, but I don't know the temperature. I removed the cpu fan and the thermal paste was black. I replaced the paste and the pc starts but everything is now slow.

It takes about 10 seconds between clicking an icon and anything happening. Even the windows start button takes this long before it brings up a box to shutdown, restart etc.

Do I have to reset something? The mobo is a genuine Intel D865PERL.

Should I replace the cpu?

what was/is the processor temp after@before replacement of thermal paste?

It will not recover at all. You should replace your CPU.

I would double check you bios settings incase the bios has set your cpu frequency etc back to it's default setting.. That's common and would make the PC run a lot slower if the frequency is set lower.