AMD's web page could give you details on the power consumption, etc. The 2000 probably has a smaller die size so has less parasitic power consumption than the 1000, so even though it's running twice as fast it might actually consume similar or even less power and have similar or lower temperatures.

I doubt that your reboot issues are due to heat myself. I'd guess a BIOS update (as Greg suggested) or a BIOS memory timing issue or something like that. Can you try KNOPPIX with it and see if it's not an OS or driver issue?

Maybe grab a copy of [link|http://www.almico.com/speedfan.php|SpeedFan] and play with the memory timing, etc. Freeware (with donations requested).

Good luck.

Cheers,
Scott.