Whilst not wishing to undermine Mixture's undoubted expertise, I would ask if he has ever used or seen Linux Mint Mate.
I have moved on from Windows XP in the past few months, using Android, Linux Mint Mate (On three old laptops) and Windows 8.1 on a new HP Laptop.
The machine of I usually use is my Acer Extensa 5220 running 64 bit Linux Mint 13, it does most things "straight out of the box". Though the Broadcom WiFi was a bit of a problem, but that is common on all Linux distros and I haven't yet cracked networking machines with dynamic IP addressing.
After years of using Windows XP, I find that it is similar, but different to XP. By this I mean it is obviously not XP, but I feel comfortable using it and things seem to work if you use XP logic. HP printers are just a matter of plugging in and HPLIP does it all and in under a minute you are asked if you want to print a test page.
There seems to be an equivalent for most things from XP, Thunderbird for Outlook Express, Banshee for Media Player, Libre Office for Microsoft Office etc within the standard Linux Mint Download, and the Synaptic Package Manager hasn't failed to find other things for me yet.
I would agree with Seacue, papabravowhiskey and Mac the Knife on this one.
Having a quick look at the Specs (American) for your Compac N600c, it has 2 USB ports and a DVD ROM drive, so loading so be achievable. The stopper will be RAM, my ThikPad T41 with 512MB can be quite slow, but it does work. The specs I saw for your machine said it will only support a max of 384MB.