See my updated results here.
Here is a snapshot of what kind of PC I ran my benchmarks on:

And here are the results.
| Browser | Result | xSlower | Link |
|---|---|---|---|
| Chrome 4.0 | 592.2ms | - | Full results |
| Safari 4.0 | 873.0ms | 1.47 | Full results |
| Firefox 3.6 | 892.6ms | 1.50 | Full results |
| IE8 64-bit | 4928.4ms | 8.32 | Full results |
| IE8 32-bit | 5051.0ms | 8.53 | Full results |
| IE8 32-bit compatability mode | 5731.4ms | 9.68 | Full results |
These didn't surprise me but it was fun just to see the comparison.