Last time I formatted this computer, when I activated my Outlook Express using Hotmail, I started getting all these porno adds from nowhere, so I had to create a new address, at least for Outlook Express. Since then, everything's been fine.
I've been using my regular email address for about a year now, I get some spam due to the GF's rewards programs, but overall not bad enough to make me want to create a new address.
If you're getting spammed really bad though, I'd say get a new address. -kd5-