Internet speed slow: upgrade router or change provider?

my roommates and i (with little computer knowledge) have a basic 54mbps Netgear router with RoadRunner cable. several computers connect to it via WiFi, including an Xbox 360 (ethernet) for online games and Netflix streaming videos. our speed and connection is poor. should we upgrade the router, change service providers, or both? also there are ~6–9 other routers nearby in our apartment complex. after changing the WiFi channel to a different channel than surrounding routers, our speed increased but not drastically.