I have a really old bechmarking program called CPUmark 99 (Copyright 1998 ZD Inc.). I think it came with Winbench 99 but it was also distributed as a standalone program. Whenever I encounter a new system one of the first things I do is give CPUmark a try. CPUmark is so ancient it doesn't care about any of the new SSE instructions or multi-core CPU's or advanced caching technologies whatsoever, but I find that it can accurately judge the "feeling of speed" of a system, regardless of the actual MHz or benchmark scores produced by other synthetic benchmarking programs.
This theory got tested recently when a co-worker built a relatively high-end gaming system for a friend's friend. They decided on the AMD Phenom X4, ASUS M3A32-MVP Deluxe/WiFi-AP, ATI Radeon HD 4850 card with 512 MB DDR3 RAM, 2 GB of DDR2/800 RAM (should've bought more), and a shiny Samsung T220 22" LCD monitor. Windows Vista gave it a butt-kicking Windows Experience Index of 5.9. But when I sat down at the system and tried running some programs, I thought it didn't feel any faster than the Phenom X3 8450 (2.1 GHz) system we have. In fact, I felt it was slower! The Phenom X3 was in a low-end Gigabyte GA-MA78GM-S2H board with onboard graphics and gets a Vista score of something stupid like 1.5 since the graphics performance is so abysmal. (It's not being used for games.)
Surely enough. The X4 system only produced a CPUmark of 275, while the X3 system produced a CPUmark of 281. Eventhough the X4 did get a lower score, I felt the slowness came from running Windows Vista with only 2 GB of RAM. But the X4 should have gotten a higher score nevertheless, since it's a faster CPU with faster components. Unfortunately, the owner took the system home and I've only used two AMD Phenom CPU's so far, so I can't make any conclusions yet.
Other systems I have tested that have gotten similar CPUmarks to the AMD Phenoms include the Core 2 Duo T5750 (2.0 GHz/667) with a score of 282. This was a ThinkPad R61i. Another with a close score is a Core 2 Duo T7100 (1.8GHz/800) with a score of 277. This was a Lenovo 3000 N200. (I don't really use Core 2 Duo's on desktops.)
The fastest system we have on hand right now is an Intel Core 2 Quad Q6600 installed in an ASUS P5K Premium/WiFi-AP. It has 8 GB of DDR2/800 RAM and is running Windows Server 2003 x64. It has a CPUmark of 332. Spiffy.