If you're going to have a play with ubuntu, stick the disc in the drive while you're booted up in windows and click on it in "my computer" if it doesn't open a menu automatically - it'll open a menu, and you can use the middle option "install inside windows"
It'll basically give you a small front-end which asks how large a file you want to use as its' "hard drive", what you want your user name and password to be, and a "next" button - pick a nice short username, like "roger" and a simple password like "dell" ;-p - it'll then read the CD and "create" the information it needs to boot "from" ubuntu on that fake partition you specified the size of.
The next time you boot the PC, after the BIOS messages, you will see an option to boot into windows or ubuntu - use the cursor keys to select which, and off it goes.
I've installed at least 3 times over the last couple of weeks after managing to balls it up trying different "non-standard" things, but wubi makes it soooo easy to do :-)
If you've got an ATI gfx card, once it installs fully it will tell you you can use a "non-free" driver for your card - it'll let you use the abilities of the card more effectively - sad to say, it'll only drop into place after a reboot though :-}
I can give you a few daft tips like how to avoid having to enter a username and password to log in as well if you like...