SunSpider JavaScript Benchmark - XP SP2 vs. Vista SP1

Is browser performance affected by OS, CPU and the amount of RAM available?

A comment made by dfolk in response to my Firefox 3.0 Beta 4 benchmarking post got me back to the lab to do some more benchmarking.  Here's the comment that set it off:

Good test, but it would be nice if you did some testing on a more commonplace computer- something like an ordinary XP computer with 1 or 2 Gb of ram. This would be more meaningful to most of your readers- Vista is used only by a small minority of computer users at this time. I question the value of the test to most computer operators when the testing is conducted on Vista, and probably with a VERY high powered machine comparatively speaking. Would such a test have similar results on a more ordinary machine? Not to pick nits, I am simply wondering what applicability your testing would have to most users.

My initial testing was done on a 3.2GHz quad-core system with 2GB of RAM on Vista SP1 32-bit.  A high power system, but since I was comparing the browsers on a like-for-like system, it didn't seem to matter.  Surely on a slower system the only difference would be that the overall scores would be higher indicating a slower system.

Well, I decided to take up the challenge.  I re-ran the SunSpider JavaScript benchmark but this time instead of running it on a quad-core beast I ran it on a Windows XP SP2 system with 256MB of RAM and a 2.1GHz dual-core CPU.  Would this make much of a difference?  Well, see for yourself:

Hardly any difference at all.  RAM, CPU and OS makes little difference to JavaScript performance.