Really in the dark about this.

[#1]

Hi.
With plusnet for years connected via netgear dg834 and ethernet cable.
to desktop computer upstairs.
This above computer is wireless capable but never looked into it.
Is 3 years old.
Wife now getting idea about wanting laptop to research family tree downstairs
Would be hard to run long ethernet cable downstairs.
Don't know anything about going wireless so may be back here for loads of help
So first things first,as far as I know wireless works @  2.4 GHz 
I have cctv camera's x2  that work on  2.4 GHz.So before going any further with
questions would this be a problem please re interference.
Thanks.
Baz.

[#2]

I can now tell you tell you they do.

[#3]

You could try A or N which work on 5Ghz for your wireless..

[#4]

An alternative to wireless would be homeplug which works over the electricity ring main. You plug one in upstairs and connect it to the router. You plug a second unit in anywhere else in the house and connect the laptop to it using an ethernet cable.

[#5]

Before you go and buy any other kit, just try changing the wireless channels on the router. Shifting to a channel with a slightly different frequency may avoid the interference.

[#6]

Quote from: ForeverArsenal

connected via netgear dg834

A bit difficult to try to change the wireless channel on that router.
The point is he doesn't want to splash out before he knows if it will work!