Switching to Netscape, or better yet Mozilla will reduce your risk of being hacked.
Hacking and virus infections are less apt to impact users of alternate browsers as they are often designed around security holes in IE and OE.
However, you still need to maintain strong anti-virus and firewall security.
Viri like mydoom infected computers by users running file attachments. Your choice of browser and mail software can't stop this kind of virus.
As to SPAM, most of the spam originates because the user gave out their email address to a site that then sold the address to make some money.
I get less than 10 percent of the spam most people complain about because I am VERY careful about giving out my email address.
Bottom line, IE is a little bit more susceptible to virus infections and hacking attacks. Still, if you rely on an alternate browser or mail client for security you will still get infections and hacker attacks.
Chas