I think its budget.

Cheap and basic is your IPtables Linux solution.
Next up are the cheap ADSL NAt routers/firewalls
Next up a pro box, something like a netscreen 5XT, these are fast and ideal for home use. They can also detect DOS and drop the packets from that source.

all in all i you need a budget from £50 to £500 and that will steer you to the right ball park.

as a side note many 'box' fiorewall solutions are Harden sealed Linux systems, such as www.watchguard.com solution.