Which operating system are you trying to replace WinME with? Assuming a Windows OS such as Win2000 or WinXP, then YES, you can upgrade WinME without losing applications, data, etc. A full reformat, then install of the new operating system is a better way to do things in order to ensure a trouble-free installation, but an upgrade install normally works fine. BUT either way, it's extremely important to do some research before making the upgrade. Make sure that all of your current applications are compliant with the new operating system. In addition, find, download and save updated hardware drivers for the new operating system. Things like your sound card, video card, modems, etc. will need to have the newest drivers to work correctly on the new OS. In addition, any installed printers may need updated drivers as well.

I've also found it beneficial to uninstall the antivirus and firewall programs before making the upgrade, then reinstall it again afterwards. Some antivirus programs require this procedure in order to function correctly after the upgrade. Follow the correct uninstall procedures for both programs when doing so.

In closing, make sure you do plenty of fact finding before jumping in with both feet. It will make the installation smoother in the long run.

Hope this helps.