Test your speed wired using an ethernet cable to your hub first, using a reliable speed test site like:
http://www.thinkbroadband.com/speedtest.html
Post a link to the graph results.
As you give so little information it's difficult to know whether it's your wired speeds that are slow or your wireless only.
Even if your wired speed was constant 120mb, your wireless speed will vary depending on range between your computer and the wireless router and the amount of interference from your neighbours routers on the same or nearby channel. It could be from 0.1 to 100mb/s depending on the range and level of interference.
Use
http://www.metageek.net/products/inssider/ to find out what is the best channel for you. Good ones to start with are 1, 6 or 11 as they do not overlap with other channels. Use the Link Score to determine which is best. The higher the link score the better.
Also, check the link speed of your wireless adapter:
http://kb.netgear.com/app/answers/de...and-throughput
If the maximum speed of your wireless adapter is 54mbps, then the highest throughput you'll ever get will be about 20-30mb/s. Severely limiting your wifi speed, even if you get full speed when wired.
For best results buy a dual-band 802.11n wifi adapter that does 5ghz and 300mbps or more.
The 5ghz band generally has less interference than on the 2.4ghz band.