yes, many Linux distros have "Live CDs" (or "Desktop CDs") that you can boot up into to try it out. You can also install Ubuntu to run within Windows with their "Wubi" installation - but it would probably help to have a fairly fast PC for the latter option.
anyway - a excellent site for info about dual booting Linux & Windows is the Illutrated Dual Boot site. the site is geared towards the Ubuntu Linux distro but much of the info is applicable to Linux in general.
I recommend Ubuntu if trying out Linux for the first time - mainly because it's so popular that any issue that may come up for you is probably covered somewhere.
I'm running Windows 7 at the moment, and I hate it with a passion. You can apparently burn an image of Linux and run it without messing with your current OS, just to test it out? I've heard of FreeBSD, Linux, and Unix, but I'm not sure which one to use. Are either of them more suited for programming?
Thanks for any help!

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