We've got a couple of threads running for the iPad & for other tablets, which you may find an interesting read:
http://www.cableforum.co.uk/board/19...ad-thread.html
http://www.cableforum.co.uk/board/19...e-devices.html
For non-Apple tablets...
The Motorola Xoom is currently considered to be the best of the Android tablets, and is the first to run Android 3.0 (Honeycomb). It's due out some time this month, and is expected to be priced at £499 for the 32GB WiFi version and £599 for the 32GB WiFi+3G version.
Samsung has a range of successors to last year's Galaxy Tab due out later this year, running Android 3.0 (Honeycomb).
HP and RIM (Blackberry) are supposed to be releasing their own tablets this year, the TouchPad & Playbook respectively. Not dates or prices yet though.
Which tablet you get won't affect which router you should get, however I would make sure that whichever router you do get, you get one with Wireless "N". I've not had cable in five years now, so can't really recommend any particular cable router.