Originally Posted by heeru
how I can go about doing so (assuming I have no CD/DVD's with Linux burnt on them and I have no partitioning S/W and do not intend to buy any).
Get linux disk (if you are in UK as mentioned above, coverdisks are a good source; as you don't mention your country YMMV, but you can buy them at a reasonable price or download them). Canonical (Ubuntu) will mail theirs out, but there is a bit of a wait.
Plug in disk
Follow instructions to install
(I've oversimplified a bit; you'll have to understand a bit - not much - about partitioning if you are going to dual boot, and the issue of making contiguous free space has already been mentioned.)
I'm thinking of installing RHEL5.
I'd recommend Ubuntu (actually Ubuntu + kde) as a place to start, but then I'd also recommend re-visiting that decision after, say, six months. Ubuntu does a good job of being newbie-friendly and has a good community, but there are others, too.