If you aren't OCing, I wouldn't sweat it. That MCP-T handles a lot, like PCI and IDE devices, onboard sound, LAN, USB, Firewire, etc., but considering none of the Nforce2 boards have any type of cooling on it, I'm sure its been addressed and noted to be in spec. Unless its really bothering you and you can't help but touch your south bridge every few hours, I'd just leave it alone.
Otherwise a kit like Pun. mentioned would work well. Most kits like that come with some type of thermal epoxy to "glue" them to your heatsink. These solutions range from pretty permanent to semi-permanent. If you decide on a kit like that, they can be had for cheaper from other sites, Newegg gouges you on shipping for inexpensive small items.
Chiz