Automatic Update problem wp 3.2.1

Upgrade bombed out: Fatal error: Allowed memory size of 262144 bytes exausted (tried to allocate 77824 bytes)in /hermes/bosweb/web104/b1046/ipg……etc…on line 824. Get message on WP login that upgrade was not completed and to continue the upgrade, but when I click that option I get the above Fatal error. Also can’t access/update Pages or Posts without a similar Fatal error. I have 2G memory on my desktop. WHAT DO I NEED TO DO to fix my problem. I don’t know anything about PHP or MySQL. Wish I could just keep the old WP version, but don’t know how to restore that. PLEASE HELP!