BEFORE using the WUBI installer, make sure you have a reasonable amount of free space on your hard drive... the installation requires a minimum of 5GB free, but you will also require approx 15% (preferably more) of you hard drive free AFTER the installation for the Windows swap file and system restore points.
By far the easiest way to install Linux as a dual boot system would be to use WUBI which will install Ubuntu 9.10... WUBI can be downloaded (in windows) here:
http://www.ubuntu.com/desktop/get-ubuntu/windows-installerSee here for the WubiGuide (instructions and info):
https://wiki.ubuntu.com/WubiGuideBear in mind that on April 29, a new version of Ubuntu (version 10.04) will be released, so if you are in no hurry it might pay to wait till then... there should be a new version of WUBI (which will install the 10.04 version) at the same URL as above on or around that date.
Just download the WUBI installer and run it in windows... the rest is automatic... it will download Ubuntu 9.10 and install it for you... bear in mind it has to download 700mb so it will take a while.
It shouldn't slow your system at all, quite the contrary you will find Windows the same as before, and Linux should be faster than Windows.
If you were thinking of using a different Linux distro to Ubuntu, it can be done but is a little more involved.
Another way of having a usable Linux system WITHOUT the need to install to your hard drive at all, is to run Linux from a USB stick... again this wouldn't affect your windows installation at all... but this will only work if your system can boot from a USB pendrive... this may not be as fast as running from your hard drive though... if you want to know more post back, or see:
http://www.pendrivelinux.com/Nothing wrong with keeping both Open Office and M$ Office if you want.
I personally don't use M$ Office any more, and only use Open Office, as I only use Linux now and don't feel inclined to give my hard earned to M$, or to be stuck with their proprietary formats
And you are more than welcome to ask as many questions as you may have
