First generation i3/i5/i5 (only dual core for i7 unless the system has a discrete GPU) -- i7620m/i7640m will work.

ok, but does the windows load up if i replace the cpu or do i have to uninstall some drivers first? or just boot it into safe mode with the new cpu then?

No changes other than installing the CPU and replacing the thermal pad is required.  That said, you're buying a CPU that's 12 years old and will likely need to buy through EBay or similar -- these haven't been made in well over a decade.  Be sure your seller has a good reputation and will exchange a CPU that arrives DOA.

The CPU needs to be from the same generation as the Pentium 6200 -- that is, a first generation Core i CPU.  There are i7s the system will take - -read the thread to see which ones.

ok thanks, it seems to be working fine, but the temp is 47-58 degrees at idle(520m), so i wonder if that is quite normal or a bit high for the new paste and cpu.

i wasnt able to check the old temp tho, because the fan was blocked by some ram cover's metal bits lol