Best way to use PHP to encrypt and decrypt?

I plan to store foreign account information for my users on my website, aka rapidshare username and passwords, etc... I want to keep information secure, but i know that if i md5 their information, i can't retrieve it later to use.

garble function contest

Remember that away message on aim that said how:

Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.