not if you install OVER your existing windows.
BUT you can likely intall it paralell to your windows. you just need to make room for it "on the side".
btw BACKUP before resizing, things MIGHT get messed up.

basically what you do for that is "shrink" your pressent Win partition about 4Gb.
then in the "empty space" (unpartitioned space) you make a 500Mb and a 3.5Gb partition there, "forMat" the 500Mb as SWAP and the 3.5Gb as ext2.
now you can install there and still have windows if you choose.
you can even setthings up so you can choose between win and Linux when you start your computer.
here are a few links with more info.

a link to a desent walktrough is here;
http://godot.studentenweb.org/debian/index.cgi

here is a BUNCH of links from http://www.knoppix.net/doc that have more info, not 100% nesesary to read it all for a hdd install but...

http://www.knoppix.net/docs/index.php/HdInstallHowTo
http://www.knoppix.net/docs/index.php/FaqHdBased
http://www.knoppix.net/docs/index.ph...serChangeHowTo
http://www.knoppix.net/docs/index.php/KnoppixInstaller
http://www.knoppix.net/docs/index.ph...stentHomeHowTo
http://www.knoppix.net/docs/index.ph...tallTweakHowTo

once again back EVERYTHING up before partitioning, it MIGHT get messed up.