If you are using Win98 or Win98SE you must change your environment variable settings for your Command Windows. This is required because Eclipse is launched from a Batch File. Please see the "Getting Started Guide" that describes the required 2048 environment requirement. However, if you are using windows XP and have installed any Windows Service Packs with the required Java Runtime libraries then please reinstall the Java Runtime Library.
Most customers who start with the Sun version first without success will have better luck with the IBM JRE. You can download a copy of the IBM version from our web site at: http://www.cypress.com/?rID=14437
As a suggestion, another resource for eclipse questions can be directed at http://www.eclipse.org./ It has been reported that the newer version of Eclipse operates better with either of the JREs.