Recovery after server crash

Good afternoon, all:

I recently experienced a server crash.  I have a backup of my Postgesql
data directory.  

On rebuilding my machine, I decided to go with i386 instead of my
original AMD64.  That means I now have a newer version of Postgresql
available to me.  My original was 7.4 and my new is 8.0.3.  

How can I get my data from this 7.4 data directory into my 8.0.3 fresh
install?  

Thanks for any advice!

Chris