@bru: You might want to test a USB network adapter to see if you get better results. Check out the reviews before you buy.
You're only going to get fair performance with economy equipment-no matter what the mfgr claims. There are all sorts of fudge factors printed on the box and in the manuals. As long as you understand what you're buying, you shouldn't be too concerned about how the numbers are presented.
Your router is only rated "Good" by the Mfgr. My Asus router is in the middle and I'm getting about the same as you - so the NIC looks to be the bottleneck. I almost invested in a better USB network adapter, but as I said, I'm satisfied with the throughput that I'm getting - so I saved the $30.
I think that if you do some research
and shop around, you'll be able to find a better router and pair it with the same mfgr USB network adapter for a little more money than what you spent on the Netgear N300.
BTW: I mentioned the ISP speed only to show that no matter how fast your wireless is - you won't see much difference if the internet is the sole purpose. I'm running at the 50/10 speed, so a wireless connection between 30 and 70 is great. Why between 30 and 70? Well, it changes based on the signal noise in my area - there are 27 routers around here, plus cell phones, cordless phones, garage door openers, microwave ovens, fluorescent light bulbs and any number of other wireless devices on the 2.4 band.