AFAK, the gaming benchmarks (aquamark, 3dmark etc)are pretty good for telling you how hot you're system is, as they use graphics, CPU and RAM together. Making those three communicate right is half the battle...
As for other tests, SuperPiMod will give you a good idea of how fast your CPU is, and it's easy to compare results.
Also, go to http://www.custompc.co.uk/
(CustomPC - a uk Magazine) then the "benchmarks" section and download their tests.
Their description of the tests:
Benchmarking is very important to us, because a product's performance is one of the most important factors in assessing quality. And, without the relevant benchmarking tools, it's impossible for us to judge which hardware deserves your cash. Unfortunately, most third-party benchmarking tools rely on synthetic tests that don't accurately reflect what most PC enthusiasts do on a daily basis. That's why we developed our own Media Benchmarks, which use real applications to carry out the tasks that most of you perform on a regular basis, and we've now updated these to stress even the latest hardware. There are three tests, each of which measure different aspects of a PC's performance. These are also the same benchmarks that we use in the magazine, so you can make a direct comparison between your PC and the kit we review. You can also submit your results to the Custom PC website and compare your PC's performance with that of other readers' PCs.
You can then check their Leaderboard for others with similar specs as you, and how you fare.