which UBUNTU release for first install to share HD with Windows 2003 server

I have 20GB unpartitioned space on my Windows Server 2003(one hard drive). Ubuntu has been recommended. It will be my first Linux install. Have done many Windows/Windows server installs and IBM i/iSeries.

Which Ubuntu release is best?

Is there a boot manager compatible with existing Win Server 2003? Do I need one? Have used IBM's boot manager with OS2 and Novell. Worked great (yes it WAS a while ago...)

Thanks,

Current release of Ubuntu is 11.10 in 2 months will be released 12.04. Most distributions use Grub boot loader.
If you are new to Linux Ubuntu is one recommended distribution. Keep in mind that Linux is not Windows.

Regards

For a server install, I recommend the "Long Term Support" (LTS) releases. The current LTS is 10.04, which will have sever support through April 2015.

https://help.ubuntu.com/10.04/serverguide/C/index.html

The "point" releases (currently 11.10) give the latest desktop apps, but only have an 18 month life-cycle; this is why I recommend the LTS for stable server use.

Ubuntu uses the GRUB2 boot loader, which has the ability to "dual boot" with Windows if you like.

You may wish to use virtual machines instead of real partitions and dual boots. Kind of hard to mess up your host OS with a VM. If your system is good enough and you have some spare ram then a virtual machine running on the 2003 would be a simple and easy way to use both at the same time.