Yes indeed, the best one I ever liked was the Ubuntu LTL 6.02 to date with VMWare 5/6 on top of Windows XP, acting as a virtual host enabling any OS including Linux variants from RH9 to Debian. The Ubuntu was so charming and simple that no Software Developer with GNU gcc/g++, Perl, Python, tcl, LAMP would ever talk of other Linux as desktop companion for Windows XP. A 20 GB of your 60-80 GB Windows with current 1-2 GHz processor will give you all that you need to compile, build, test, document, QA, release, bug fix, and besides all the Open Office cool stuff matching the Windows XP / Office, even vim / Emacs and for a while I really forgot about Windows XP. Just used for almost 60-75 days as Linux desktop, until I had to switch to Visual Studio for some .NET development.
To test this out on your Windows/XP host...
1. Buy a VMware Workstation 5 Handbook by Charles River Media ISBN 1-58450-393-9 to install a VMWare WS 5.5 or higher or download a 90-day trial form www.vmware.com and get a 90-days key.
2. Create using VMware install media/download a partition of say 20GB to install and mount Linux (select unkown Linux version in VMware Menu).
3. Download the ISO file about 700 MB CD size, for Ubuntu LTL 6.02 or 6.10 Desktop version from www.ubuntu.org.
4. Using VMware identify the ISO file for install and complete the install of Linux, may take an hour depending on the speed of your Windows Host. You will be a user with root permission.
5. Using a terminal or console once Linux is installed, add any of the Debian's 14000 strong binary distribution softwares fro m Internet using simple Firefox inbuilt browser. Note while installing Linux over Windows, if you have a local DHCP nework, just bridge with existing Windows Ethernet card, that is the simplest and easy. When you are not using any way you will shutdown the Linux (Ubuntu) instance and thus windows host will work with it own IE flavour and its idiosyncrasies.
Just to ensure smooth downlaods (you may need wget package install before you can download and even update your Desktop Linux from Internet form within Linux.
(Get wget for http based command line downloads like ftp)
$ sudo apt-get install wget
wget installed.
$ sudo apt cache find
$ sudo apt get install
Some packages can be like gcc , vim and Mantis and all open source that is available under Debian binaries. Even you can get sources and build/make if you are a software developer as most of Silicon Valley peopel are.
The other variations like RH9, SUSE, even Debian, Fedora , Solaris 9, FreeBSD are installable under VMWare 5/6, but once you use Ubuntu Desktop, the choice will become clear. I wouldn't be surprised if school kids will start jumping from Mac OSX to Ubuntu for their class & homeworks in time to come.
Best luck and join the Open Source movement for better IQ development.