Network Setup Help

I am not a huge tech person as far as making everything work seamless and to it's fullest potential

I currently have an old Linksys BEFCMU10 cable modem paired with a Linksys WRT54GS (G) router.

I am anticipating buying the new iPad in a few days and I'm trying to get my network up to speed before I add the extra load. Currently I run a Roku most of the time for all content and a laptop for my internet access with the occasional smartphone mixed in. I am assuming the iPad will be N compatable and my current laptop is. I just never wanted to invest in the money because G was more than fast enough for my laptop. My stuff is so old I don't know if the router can handle the extra strain. I ran some speedtest.net tests this morning and this is what I got:

Wifi

Up down

2.76Mbps 10.06Mbps

2.78Mbps 9.37Mbps

2.85 16.11

2.81 12.11

AVG: UP =2.8 Down=11.91Mbps

Plugged in

Up down

2.84 26.43

2.83 26.79

2.84 27.34

2.84 26.08

Avg: UP=2.83 Down=26.66Mbps

So the question is this. I'm debating between the linksys E2500 dual band and the E3200. I can't seem to be able to tell the difference. I'd love to save the money but since I plan to keep it till it fries I'm fine with spending the extra money. Is it worth it to go with the 3200? To me they both say dual-band...so I'm not certain what the difference actually is. Also do I need to upgrade the modem as well?