Virgin Mobile uses Sprint's CDMA EVDO network. The max download speed you could ever see would be 3.1Mbps. In reality the fastest towers will sit at around 2.5Mbps and most sprint towers struggle to reach 1Mbps.
While there are some slow dsl providers out there, CDMA EVDO will never compete on speed with DSL I'm afraid to tell you
What kind of speeds are you seeing?
Treat this like a mobile phone (since it really is)... try moving it to a window or another location to see if it helps get your speed up.