Vista - I need to recover an email account password from an IAF file

Can someone tell me how to freely recover
an old mail account password I lost when changing machines
it was in the form of an IAF extension all the
account information but it is encrypted
and I need that same password to get access to other
things besides email which works A-OK ??

I might go to my ISP but because it is a gift
it resides under another persons data.
I have all I need on my own machine
WHICH I OWN and ADMINISTER but
cant for the life of me recover a stupid password
which is my own. ??

The IAF extension is an exported account.
All the data is there but it cant be read.

Also is there a way to not encrypt passwords
since I am the only user of this machine ??

Win VIsta Premium OEM version SP2.

Thanks for any realistic answers.
geoff