Edit: I'll leave the original post as-is, but after further investigation, it appears that the problem is something to do with my wi-fi card. Speeds are normal when I connect via cable.

Edit 2: Problem was solved. It was something to do with the wireless card drivers.

I normally use Windows 7 on my laptop and have internet speeds that are normally about 15-20 Mb/s. I have recently dual-booted with Ubuntu 12.10, and have noticed that internet speeds are drastically slower in Ubuntu. When tested, speeds range from 0.2-2 Mb/s, although occasionally being significantly faster than that or even stopping completely for short periods of time. I've also noticed that when first booting into Ubuntu, speeds start fairly fast, and drop to incredibly slow with a few seconds to a few minutes. There's still some possibility that the issue may be with my ISP, as things seem slower than usual even in Windows, but I suspect that it is related to Ubuntu, as things are far slower in Ubuntu than in Windows. I'm wondering, what could be the cause of this?

Potentially relevant information:

-I've dual booted before on this machine with earlier versions of Ubuntu (different ISP at the time) with no problem.

ISP: Rogers (Major Canadian ISP)

System info (Gateway NV53a Laptop):

Operating System

MS Windows 7 Home Premium 64-bit

CPU

AMD Phenom II N970  
Caspian 45nm Technology

RAM

6.00 GB Dual-Channel DDR3 @ 664MHz (9-9-9-24)

Motherboard

Gateway SJV51_DN (Socket S1G4)  

Graphics

Generic PnP Monitor (1366x768@60Hz)
ATI Mobility Radeon HD 4250 (Acer Incorporated [ALI])

Hard Drives

733GB TOSHIBA TOSHIBA MK7559GSXP ATA Device (SATA)

Networking info: Connected through Wi-Fi

    Atheros AR5B97 Wireless Network A