>my recommendation is that if you are using a normal hard drive (usually including the SSD drives that emulate normal hard drives), allocate a 2G swap partition and leave overcommit enabled (and that's probably a lot larger than you will ever use)
FWIW, I agree, except that I'd make it a file instead of a partition - it's just as fast, and it leaves some flexibility just in case.
I use a 2GB swapfile on machines ranging from 256MB to 8GB of RAM - it may be overkill but that much disk space costs next to nothing. I wouldn't want to set it higher, because if I'm really using swap to that extent, the machine's probably past the point of usability anyway.