Yes, it is worth the money...
First of all, the DWA-160 is a dual band 11n card, so to get the most out of a setup with this card, you need to have a dual band 11n router (DIR-855 in th EU). This is to devide up your wireless load onto two bands (the 2.4GHz and the 5GHz).
You should never have the IEEE802.11b mixed with 802.11g or 802.11n. the 11b has a complete different modulation than the 11g and 11n and will drastically slow your wireless network down.
If you must mix, use the setting "11n and 11g only". the differences between 11g and 11n are not in the modulation of the signal, but in the way the data is sent, so this will not have such a big impact on your performance. Having a 11g unit transmitting in your 11n environment will effect the performance, but not so much.
One more thing to consider is that 11n must care about neighbouring 11g networks, so place your channel as far away from the souronding 11g networks as possible. If the router hears an 11g unit close to it's own frequency, it is forced to lower the channel width to 20MHz instead of the faster 40MHz.
Just a tip..
