New computer - how to transfer old system across?

[kony]

I think I can get a card for £5
http://www.maplin.co.uk/module.aspx?TabID=1&criteria=ethernet&ModuleNo=31868&doy=27m4

I assume utwill work in my mobo
http://www.uktsupport.co.uk/pb/mb/850.htm

Yes, your board has 3 PCI slots.

Looks like I am looking at £30 (~$50) for a router from a similar shop.

I don't know the UK market, but in the US they are always
cheaper. If you have weekend newspaper ads you might find
something in them, or perhaps ebay?

I may try to do something with a crossover cable first before I spend
that kind of money, I only have one monitor at the moment anyway.

You can indeed use a crossover cable for peer 2 peer, or if
you didn't have the crossover cable yet, you could buy a
Gigabit network adapter as they have auto sensing (part of
the spec for GbE) and will work in peer 2 peer with a
straight rather than crossover cable. The 'site you linked
had one Gigabit card but it looked overpriced... at least
here in the US we can get a generic PCI gigabit card for $15
delivered, maybe even less today.

This looks lilke it could be useful
"Primarily used for straightforward networking of two PCs. Simply connect
the LAN ports of two PCs or laptops with a cross-over cable to create a
netwok
with no additional hub required"
So I could connect then for £10 in total

I would also have to look at compatability considerationsifI switch from
cable to ADSL.

http://www.maplin.co.uk/module.aspx?TabID=1&criteria=Network Cables&ModuleNo=47616&doy=27m4

The typical modern routers will work fine with either ADSL
or cable modems. You would not need a crossover cable for
one either, and some also come with a (fairly short, perhaps
2 to 4 meters is average length) cable.

I am not entirely convnced it is more secure myself, there is still
a path through to your PC, afterall I am behind a 'sophisticated'
ISP and if thay can't protect me then who can?
Maybe they can't afford a router either :O) ?

You still have a learning curve, about routers, and Windows,
before you will understand.

The ISP does not protect you from much of anything. They
pass all traffic with rare exceptions. Their router(s) does
not protect you at all. Your router is another matter, it
can and does control access to and from your lan and
prevents any open windows ports (or some 3rd party malware)
from having open communications. You would do well to
educate yourself a bit more about routers and Windows
flaws/vulnerabilities/etc before jumping to conclusions. It
IS the preferred choice by experienced users and security
experts alike.