If you are trying to import a database that was exported with something like mysqldump (basically a big text file) i would use the command line instead of myphpadmin
-from the command line as root type 'mysql -p' and log in
-in mysql type 'create database foo' or whatever the name is and then exit
-back at the prompt type 'mysql -u root -p password foo < dumpfile.sql'
done deal. as far as memory limits in mysql, yes, there are buffer limits depending on the type of database (isam, innodb, etc) but you would have to look through your my.cnf to figure out which one may be causing the problem (there are many).
also keep this in mind, importing a database that was exported in, let's say, mysql4 might not import into a mysql5 server.
I am root. If you see me laughing you better have a backup.