You should not have wireless and wired connections enabled at the same time on each laptop; choose only one.
For example, if you have Wireless G enabled on your laptop, but it's also plugged into the ethernet; most likely Wireless G will have priority and you will be stuck with 6 MB/s. Wireless G is limited to 6 MB/s (54 Mbps).
Also, check your hub ports because they could be ethernet 10/100 which is maxed out at 12.5 MB/s (100 Mbps). Gigabit ethernet; however, will have plenty of extra bandwidth to use your fibre optic connection 35 MB/s at full speed.