<< I thought I read somewhere that you should set the swap at twice the ram... >>
That's wrong. If you have less RAM that someone alse, you need bigger swap file that he does. AFAIK the best way to set size of swap file is to use System Monitor. Let windows manage your virtual memory and after heavy usage of your computer for one full day, check the peak value for "Memory Manager: Swapfile in use". Set minimum size of your swap file to this value. Don't set maximum size (some day you might be using your computer more "heavy way" than usually and windows will be needing more virtual memory. Now, if you have placed your swap file on dedicated partition (I believe it's not such a bad idea), I would set size of this partition to anything above 150% of your swap file minimum size.
I hope it makes some sense...
Cheers,
SB