Using two devices off my router

[#1]

My laptop works fine with internet connection on its own (off my Thomson 585 router).However, as soon as I switch on my Archos 70 internet tablet, I keep my laptop connection but get zilch on my Archos. To check it wasnt the Archos at fault, my brother got no internet connection with his ipad2. I have changed router channels, and done all the other suggestions including checking with plusnet customer service but nothing.
Can anyone help. Why can I not get a internet connection on my Archos when using my laptop at the same time?

[#2]

If it's a TG585v8, first try switching the wi-fi from b+g+n to b+g or g only, the 'n' on these can sometimes cause trouble.

[#3]

Hi caldal,
It doesn't appear that the Thomson was supplied by us, as I can't see it on your account. Is it a v7 or a v8?
Jojo