Another resource is http://distrowatch.com/dwres.php?resource=major
It has good descriptions of 10 of the popular Linux distros.
My preferences at this time are Linux Mint and Fedora.
You can download the distros and burn them to a DVD or, if you are bandwidth limited, you can get disks from osdisc.com for $3 to $6 a copy.
Also, get the live/install versions. You can try it out in live mode and if you like it, just hit the Install icon.
If you don’t want to remove your existing OS, just make your computer dual boot. When you start the PC, you will get a screen that asks you which OS you want to start. Of the distros that I’ve tried, Mint is the easiest to do this with as you don’t have to mess with partitioning the HDD unless you want to.