Wireless download speed far below expectations

[#1]

Hi folks,
I've recently had the Plusnet 74Mbps fibre optic broadband installed, but I'm having problems with the wireless download speed. I'm in the midst of being sent a new router, but like lots of people here, I'm sure, I'm keen to find out more information in the meantime.
The line was tested by the engineer at 71Mbps, and while I can get 67Mbps when wired, I'm getting less than 30Mbps on wireless, despite having a full-strength wireless connection. My wireless dongle appears in Device Manager as Realtek 802.11n USB Wireless LAN card, and states 150Mbps on the dongle itself. I expect some loss with wireless, but obviously not to get less than half the 71Mbps found by the engineer.
I was previously with Post Office, and when using their 8Mbps package (Netgear DG834GSP router), I was getting at least 90% of that on wireless, with the router etc in exactly the same place as my 2704n Plusnet router is now. I am also using the same PC setup.
I was directed by Plusnet to check all the channels, which I have done, with no difference - overall, the 30Mbps I'm hitting for wireless is quite consistent across all channels. Interestingly, my upload speed is also pretty consistent at around 16Mbps, so it seems largely unaffected by whatever issues are occurring with the download speed.
Has anyone experienced a similar issue or offer any further suggestions while I await the new router from Plusnet?
Thanks!

[#2]

A n150 wireless card won't be operating at 150Mbps by default, because doing so would use most of the available channels (requires using 40MHz mode). So it would likely only operate at a max 72.2Mbps wireless rate. Then there are substantial overheads with wireless, so 30Mbps speeds seen on downloads sounds about right.
In summary, it looks like your wireless adapter is the limiting factor, and a n300 wireless adapter should do better. A new router won't change that.

[#3]

Thank you. That being the case, is there any consensus on the best N300 (or greater) wireless adapter to pick up? I'm on a Windows PC.

[#4]

Just done a test across my network using a 2704n @ 144mbps and a macbook pro also @ 144mbps
Result over UDP to a 10/100 card sending 100mb of data
Result.... 76mbps with 22% loss
[tt]------------------------------------------------------------
Client connecting to 192.168.0.12, UDP port 5001
Sending 1470 byte datagrams
UDP buffer size: 9.00 KByte (default)
------------------------------------------------------------
[  4] local 192.168.0.18 port 61643 connected with 192.168.0.12 port 5001
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-10.0 sec   120 MBytes   101 Mbits/sec
[  4] Sent 85468 datagrams
[  4] Server Report:
[  4]  0.0-10.3 sec  92.9 MBytes  76.0 Mbits/sec   2.765 ms 19221/85453 (22%)
[  4]  0.0-10.3 sec  1 datagrams received out-of-order
[/tt]
6 meter away upstairs

[#5]

So, that contradicts the idea of needing to upgrade my N150 adapter?

[#6]

If I do need a new wireless adapter for my wireless connection (74Mbps) is there a need to get an n600 adapter over an n300?

[#7]

11110_110's "macbook pro also @ 144mbps" connects at 144 because it's wireless hardware is n300 class or better.
n600 devices are typically dual band, capable of 300Mb on the 2.4GHz band and 300Mb on the 5GHz band. The 2704N router isn't dual band, so a n600 wireless adapter wouldn't offer any advantage when used with it, but would be able to use the 5GHz band if you decide to get a dual band router at some point.
I got a TL-WN822N, but I didn't buy it for speed, it's better at getting signal diagonally from one corner of my house to another, which an old 11g usb adapter isn't that good at.

[#8]

Real life wifi speeds.
http://www.speedguide.net/faq/what-is-the-actual-real-life-speed-of-wireless-374
And these are pretty much when right next to the access point, and assuming you are not getting interference from neighbors wifi.
Bottom  line is if you want to get your full 70+mb/s you need wired.

[#9]

Thanks everyone. I expect a drop-off between wired and wireless, but if I can't get 50Mbps or more on wireless with the Plusnet equipment, I'll probably just downgrade my package.