When to apply new thermal paste?

[onlyCOpunk]

Alright I took out my XP 2400+ and while I only used it for a couple hours, AMD says that if the paste gets dirty to replace it. But I plan to use my CPU and heatsink again, do I need to buy more thmeral plaste and reapply next time I install or if I package them up right and keep them clean should it jsut work fine?

 

[ChampionAtTufshop]

generally everytime you take the heatsink off the cpu you should clean off the existing thermal paste and reapply some more