New computer, internet connection issues?

I've just put together a new computer and it was working perfectly for the first couple of days.

I was using a wireless connection via a USB dongle and after the first couple of days it started cutting out more and more regularly whilst 2 iPhones and 2 iPads were unaffected, I replaced the dongle with a new n900 wireless card and the same thing is happening.

Upon further testing my iMac (which I had planned on selling due to building my computer) also stays connected wirelessly.

What is weird however is that when I use my own iPad (which is on a 3/4g contract) as a hotspot, my connection is perfect, never lags, and never cuts out.

I don't want a workaround where I use my iPad as I'm paying for broadband for a reason and want a better service.

What could be the reason behind me cutting out? Is the router clashing with my PC or what?

You should consult a technicians to your home, if your 2 ipad and iphones doesn't have a problem in your wireless router, and you buy wireless adapter, that is your computer problem ok you should test your computer via lan cable connected, if that is fine, you are facing some driver issues or malware, just download jrt

1)Change the broadcast channel on the router to channel 11 or 2 steps higher or lower than the current. You can download netstumbler or inssider (google them) and they will display the broadcast channels of any neighbouring Wi-Fi networks

2)Turn off any baby alarms cordless phones wireless doorbells as these use the same 2.4Ghz frequency

3)Update the firmware of the router and drivers for your PC/laptop
HTH
David