Hi u2. 55C isn't too hot for a processor, but it's a good idea to keep it below 50C if you can. You say that a new heatsink is too expensive. An AMD recomended heatsink for your Athlon XP2000 is £5.57 inc vat from E-Buyer click here. They also have a case fan for under £1. I wonder if you damaged your processor when it severely overheated, or if your motherboard chipset or graphics card is getting hot. A case cooling fan could help keep everything in the case a bit cooler.