My PC is four years old and despite housekeeping and defragging it is on its last legs so its time for a new one.
How do I transfer everything on this PC to the one I buy (Outlook Express, my photos and videos etc)?
if you gonna be buying from a local shop theyll probably do it for ya free
but if ur buying from pc world etc theyll chrge ya
i,ll have a look and see if i can find an idiots guide that we had to draw up at college last year for ya harry
Have a look at this Harry and see if it’s any use. 
old to new file transfer
you can get a kit that will allow the old hard drive to connect through a usb port and you can transfer everything that way or backup everything on to dvd before it goes pop
To move Outlook Express look here, this works I have used it a few times.
As Alix776 has said there is kit available to allow you to connect the h/drive out of your old PC to your new one via USB,
then you can browse it like any other drive and copy stuff off it. I’ve done this a number of times, so long as you don’t mind removing a h/disk from your PC then it’s a doodle.
why not just take the hard drive out of the old one and put it in the new pc as a slave, 2 hard drives and all your stuff (photo’s, video’s) is there
Cos his old PC probably has an IDE drive and his new one will be SATA drives,
and probably only has 1 IDE slot on the m/board used by the DVD drive,
so he’ll have to mess about with the jumpers to set a master and slave,
assuming it has 2 IDE connections on the ribbon cable.