Will an 802.11b adapter work with a 802.11n router?

Our office recently purchased a new 802.11n router. All of the laptops have adjusted with no problems. The lone ancient POS desktop uses a linksys 802.11b wireless adapter with our old router, but seems to not want to connect to the new 802.11n router. Are they simply incompatible, or is there a fix?

Thanks.