Swap size = double the RAM size

Since aeons ago, even my grandma will say "hey, your swap size should be double the amount of RAM you have". WTF, mate. The more RAM you have, the less likely you'll run out of physical RAM, and the less swap you will need. And more importantly, the less RAM you have, the more swap you need! People go and set 512 MB of swap size for a 256 MB RAM machine. Retarded; I'd go for at least 1 GB. Then people go and set 2 GB for a 1 GB RAM machine. Retarded again, that's when I wouldn't mind 512 MB.

This goes especially for Windows NT, which (what's better than Linux) will swap in an unfragmented file and will dynamically allocate more space as necessary, so, if at one point in time you buy more RAM, you might need to claim some swap space, and if you get more bloatware and need more RAM, you might want to expand and defragment it for maximum performance.

You can use files for swap in linux too, although it won't automatically resize.

As for size, the 2x rule clearly has been outdated for some time now. It depends entirely on the system's program mix.