It depends if you Dualboot, you can have 2 OS's, you just need a not shitty HDD. Or you could just delete your current partition and replace with a new one w/ a new OS. What Linux do you want? Redhat? SUSE? Ubuntu? I use Ubuntu and I like it but Peaches prefers SUSE.
Its just the freedom of having another OS IMO. I just get bored of Windows and I use Linux when browsing the internet because nobody makes virus's for that OS.