Can I use a bg router as an access point with a wireless n router?

yeah unless it has a very bad software system that doesnt allow for using as an access point to begin with. the generation of wifi doesnt matter.

"Can I use a bg router as an access point with a wireless n router?"

If it supports being configured as an access point, and you wire it to the "n" router.

But most routers capable of "n", also provide services to "b" and "g" networks.

Generally, yes. Computers connected to the b,g access point will be limited to b,g speeds, of course.

Provide more details if you want more information.

uhmmmmmmm WITH?? you dont wanna really put TWO routers on your network, unless you know what youre doing. im going to assume you do, and youre asking if the two types of protocols are compatible. yes, the N router should be able to understand previous versions of 802.11 (wifi). now, if you truly did have a reason to put 2 routers on your network, you would know enough to not have to post on here. so just dont do it. dont put two routers on ur network.