If I can't use my current drives I might as well keep this PC for a lot longer, scrapping a few hundred GB of storage is a pain - not to mention transfering it across.
If I replaced MB and Chip - what could I go up to?
That was my point, so is it worth throwing another £60 - £80 on a HDD at it. You cannot buy anything as slow as a 2.4G P4 on a SIS chipset now. You've already added a midrange card recently. You are putting a lot of money in to an old system.
I would not entertain the idea of putting in a sub optimal mobo just to use old drives. PATA drives have horrible cables from cooling point of view (the round ones are OK ish), and not many drive vendors are releasing new drives on the old interface.
Just checking Dell systems for my brother, £450 will buy 2.8G P4 dual core, 1G RAM, 250Gb HDD, 16x DVD, 17" lcd, bluetooth keyboard and mouse, XP MCE (OEM) etc etc. Not state of art by any means, but a great, super quiet, general purpose machine.
I am not recommending that system to you, as I don't know your requirements - the onboard video may be limiting for your requirements - probably slightly/noticably slower than a Radeon 9600 or Nvidia 5500 that I think you have?
The thing with Dell is to find a system that meets your needs, rather than respeccing one (expensive) - Dell change their deals weekly, on a Thursday morning. Good site for overview of current deals is
http://www.dmxdimension.co.ukFeel free to PM if you have specific Q's you don't want to publically post about...