Two fantastic system monitors have been updated. First we have Process Monitor from Sysinternals which monitors tasks, registry activity, file activity and network activity, all of which can be logged. Great for de-maling a PC or just finding where that shareware program posts it's timeouts.
Secondly we have HWMonitor from the makers of CPU-Z. This handy monitor displays voltages, temperatures and fan speeds of CPU's, HDD's and Video Cards without installing a system driver - completely portable.