Why don't you use a spam filtering application? There are plenty around. Even the spam filter built into the newest version of Outlook is solid.
I changed my email address about 6 months ago and used a number of aliases for non-private email. I don't get any spam on my personal email account. In fact, I don't get any spam on my aliases either although I do get some on my info@ address for my business. The spam filter takes care of 99% of it.
As for tracking down the emails... You can try
www.SamSpade.org for some standard tracing tools. I'm not aware of email tracing tools but I know they exist.
If you you find the source of the spam, not good odds, what then? If they're not in the U.S. you've got no options. I recently read an article about a guy in the US suing a Pennsylvania-based spam company after they wouldn't meet his "out of court" demands ($250 per spam message). He had logged quite a number of spam messages.