You can download it here.QUOTE
SeaMonkey 1.1 is now available. Powered by the same engine as Firefox 2 and the upcoming Thunderbird 2, SeaMonkey 1.1 includes numerous enhancements including more visible security indicators in the browser and enhanced phishing detection for e-mail, a new tagging system for e-mail that supersedes labels, support for multi-line tooltips in web pages, and previews images in tab tooltips. Other changes include inline spell checking in the browser, an updated version of ChatZilla, and a significantly improved startup script on Linux. See the release notes for a more complete list of changes.
Seems to run fine on my G4.