So I just bought an Airport Extreme simultaneous dual band base station about two days ago for $179 but now have come across a friend of mine selling their 500GB Time Capsule for $125. I had plugged in a 160gb 2.5" SATA drive into an external enclosure and into the Airport Extreme for time machine backups. The initial 40.5GB backup took about 4 hours. My question is that if I get a Time Capsule, would my transfer speeds increase due to the drive being built into the router or would they decrease due to not being dual band (I have several wireless G devices in the apartment that would probably drop the data transfer speeds to 54mbit instead of 300mbit)? I'm trying to figure out what the best bang for my buck is here for a solid router and decently fast wireless backups.