[ALUG] Prescott - how many CPUs???

My Nephew, who is a bit of a computer whiz, recently gave me an 'old' 2.6GHz Prescott CPU to replace the Celeron in my desktop PC. This I have done and it is certainly faster. However, I use gkrellm to monitor resource usage and whereas with the Celeron just a single window occurred for the CPU usage, now with the Prescott gkrellm shows two windows labelled CPU0 and CPU1 respectively. Googling Prescott I can find no mention of more than one core but it does have hyperthreading. So my question is, how many (effective) CPUs do I have and is gkrellm accurately reflecting them?? Cheers ian