...well - basically you install WindowsXP on one disc and Linux on the other
there is not too much to it - really!
I'd suggest to install Win on the first primary disc and linux on the second - I know that it was at least not very easy to install older Win-versions in any other place than on the first partition of the first disc.
This is not true for WinXP - as far as I know - but to avoid possible surprises i'd recommend this.
For Linux you need at least 2 partitions on the (second) disc - one for the entire filesystem and one for swap.
How you install Linux depends on which Distribution you want to install and use - I know the Debian/GNU way and the Suse way - they are both pretty easy to install initially.
If you know the names linux uses to refer to discs - and _something_ about the different (compared to Windows) layout of the filesystem, it is not a difficult to do.
Linux uses the names: /dev/hda? for the first disc on primary controller
/dev/hdb? for the second disc on primary controller
/dev/hdc? for the second disc on primary controller
/dev/hdd? for the second disc on primary controller
the question-mark being a number from 1 onward - this is the number of the partition on the disc.
So to install linux on the second drives first partition you would install it into /dev/hdc1
To get a little familiar with linux I suggest you get a copy of Knoppix - a CD-Rom which you can put in your CD-Drive and boot and use without installing anything.
To be able to boot from a nice screen - which presents you with a more or less nice menu to choose which system to boot - you will have to install a boot-manager on the disc your bios tries to boot from - normally the first disc, but this can be changed in the bios-settings of your PC.
I only know about bootmanagers for linux - this only means, that you install and configure them from inside linux - of course you can boot your WindowsXP with them too!
I'm using one named "lilo" to boot my PC which has linux and WinXP installed.
But to install and configure it, you must be using linux - and know how to do it - which means reading documentation.
If I where using two discs as I described it, my configuration file would look like this:
(the bitmap and following things provide for a pretty nice screen with a menu to chose what to boot)
How about trying it and see if it is really a problem - like you said?
There is lots of information and there is google...