Copy DataBases Server to server

Hi everyone,
I've a problem that i'am not able to solve alone (i'm kinda newbie on
postgresql).
we were running PostgreSQL 7.4 under Linux (Mandriva) but our HDD crashs
and we lost the system but were able to backup the database files to an
other HDD.
now we want to copy the databases  to our new server but it runs
windows XP Pro 64bits and PostGreSQL 8.0.
I try something simple, copy the former databases files in
postgresql\data\base but it doesn't work (i knew it won't be so simple)
and i look the 3 .conf files but i've found nothing intersing for my
case. I could easyly rebuild the relationship, but re-importing the data
will be a last option (it takes a few days the last time).
I'll go with the questions:
First: Is it realistic to think that what we want is possible?
second: if yes, Is it for PostGre Gurus, or will i be able to do it?
third: thanks, that's all!