The 4620L will allow twice as many simultaneous connections than the 4510L (10 vs 5) and has a different interface, perhaps an upgraded internal antenna. Other than that if you have to pay for the upgrade, keep the 4510L. -- ... need help? »evdo-tips.com/
The only reason I ask is if the 4620L allows text messaging through its web interface as the 4510L does not allow texting (unless there is a firmware update that I don't know about). I went into the Verizon store today and they gave me the runaround about upgrading the firmware and I would do it myself except every computer in the house is a Mac and I don't have access to a PC (which I think is necessary to upgrade firmware).