I bought a newer processor for my computer (Acer Aspire AM1201 with AM2 socket, only a few months old) and I'm upgrading from a single-core Athlon LE-1620 to a dual-core Athlon 64 X2 5600+ AM2, and I just realized I need to know a couple of things.

First off, what is the likeliness of my motherboard accepting a single-core processor but not a multi-core? I seriously doubt it since the computer's only a couple months old, but I figured it'd be important to ask.

Secondly, does a processor replacement EVER require an OS reinstallation? I've had mixed responses on this and since this is my first processor upgrade, I'd rather not assume anything.