"...amp back to see what the problem was and they said the guitar was just too hot for that little amp."
You should of told them you had a volume control on your guitar. Sounds to me like the amp had a bad resonance, which could be a function of the speaker and.or the amp's EQ.
Sean, you can get that metal sound from either the amp's electronics or by adding a pedal. For cheap I recommend the Korg AX3G multifx pedal ($50 at
Musiciansfriend, follow Kirks "Stupid Deal of the Day link on the sidebar). You will be able to get metal sounds from your current amp.
If you want an amp there are lots of recommendations here, including the Roland cube. So far my experience is that I don't want a combo with less than a 12" speaker regardless of the wattage. YMMV