Congrats for giving Linux a try! The Ubuntu family is a very stable Distro, and is capable of so much and also looks great.
First off, you'll need to download a file and burn it to a CD, then boot to the CD; you cannot install while in a Windows environment. Go to
Kubuntu.com and click on the download tab. Then choose your location and select from the download sites. You can choose any of them, but one that is relatively close to you would be your best bet. It's almost a 700 MB file, so it may take some time to download. After it's downloaded, you need to burn the file as a .iso image to a black CD. You must burn as a .iso, just burning the file will not work. I like Deep Burner for all my .iso needs. Deepburner.com I think is the website, but just Google Deep Burner and you'll find it. When you are burning it to the CD, you always want to do it at the slowest possible speed your CD drive can do. 4x or even 2x is preferable, but 8x will be fine also.
After the file is successfully burned, you'll have what is called a Live CD. A Live CD is one which you can access without installing to the HDD first. When you load the Kubuntu Live CD, it temporarily installs itself to your RAM, so you can actually use the entire operating system via the CD - it's pretty nifty. Just pop it in your optical drive and select to boot to that device. It will take a long time to load at first because you're using the CD for everything, and while you are using the Live CD to look around, it will also be sluggish because of the drain on your system resources. After it's installed though, you'll be flying. To Install, just click on the Install icon on the Desktop, answer the questions, and it'll start.
The Install process is guided from start to finish, so you're always kept in the loop. You'll have to choose your language, time zone, user name/password, and disk partitions. You really only need two partitions, but my advice would be to create at least three. One needs to be a Swap (no more than 2 GB will be plenty). The second one can be your /root partition (the actual OS). You can just have Swap and /root and be fine, but I like to break it up a bit more so all my personal files will be safe in case of reinstall. Here's how my Linux HDD is partitioned:
2 GB Swap
(formatted as Linux-swap)
7 GB Ubuntu /root
10 GB Ubuntu /home
7 GB Kubuntu /root
10 GB Kubuntu /home
(formatted as ext3 or reiserfs, forget which)
40-something GB personal folder for backups
(formatted as FAT32)
At the end of the Install process, the CD will look for other OS's on your system. It will then tell you what it has found and install GRUB. GRUB will allow you to choose which OS you want to boot into after turning on the computer. GRUB overwrites the MBR and plays nice with all OS's. Windows MBR on the other hand, isn't other-OS friendly. Always install Windows first, then Kubuntu if the need ever arises.
Your HDD's will be fine and will not affect your system's performance.
I would definitely read up a bit more on the Ubuntu family. While everything install-wise is very straightforward, you may want a good understanding of the how/why combo during the install. If you haven't already, please visit
www.ubuntuforums.org, or
www.kubuntuforums.org. for some very good reading. Ubuntuforums.org sees much more traffic than Kubuntuforums.org does, but aside from different GUI's the OS's are the same on the inside, so posting on the ubuntuforums with Kubuntu questions is perfectly fine.
Thanks! Yes, there is a 64-bit version of Kubuntu as well. Once you've selected a download location, choose the "64-bit PC (AMD64) desktop CD" option as opposed to the i386 one. But, I'd also stick with the i386 one though until you get a feel for it. I loved KDE and specifically Kubuntu 6.06, but whored out to Gnome's uberness when 7.04 came along. I still boot into 6.06 on occasion just for fun though