Hello,
Can you recommend me a fast OS with GUI for my VMWare which is highly optimized specifically for an Intel Core 2 Duo (64 bit) laptop? It doesn't support visualization so it must be 32 bit. 5-6 years ago I've used Gentoo, Slackware, Knoppix, FreeBSD, Sun OS, RedHat and Ubuntu on my desktop so I have experience in setting them up. Also what desktop environment would you recommend?
Thanks

Really all of these distros would do well, and it's more of a question
of what you want to install and run on the distro. In other words,
if you install a distro "with everything" it's not going to run as
responsively as the same distro with a minimal installation.

Is there anything that you need to run in Linux? If so, just make
sure the distro easily supports it.

Who/what will be your primary support? If it's a person, get his/her
advice. If it will be Google, probably Ubuntu would be a good choice.
Unless you have a preference, go with the default desktop environment
for the distro. That will make it easier if/when you need to work
with documentation or advice from forums.