Qwest's speed is 1.5MB/download (can get up to 7MB) and 256k upload. Mediacom's upload is also 256k but has a higher download speed.
Qwest.
Actually Qwest is 1.5 MB download 896k upload not 256. The 256 upload comes with the 256 download package not the 1.5 MB.
Like someone else mentioned, unless you are a gaming geek you won't notice a difference. In fact there are some myths behind Mediacom's actual speed and what they advertise. If you want to test your actual download and upload speeds this is a good site: http://www.dslreports.com/speedtest
Here is the biggest difference between cable internet and DSL.
Cable: Shared bandwidth. The line coming into your house is shared with your neighbors so you will never get the max bandwidth unless you are the only one on your node using it. If you have several neighbors that use cable internet and some of those are gamers or constantly downloading large ammounts of data it greatly decreases bandwidth for everyone on that node. Also, Mediacom tends to "cap" their upload speeds which is where some of the things you may use online such as instant messengers, FTP, online gaming, etc. that send data back is where you might notice the differences.
DSL: The line coming into your house is dedicated just to you. This means no matter how much your neighbors use DSL, that line is not shared with your neighbors and you will always have 100% utilization of available bandwidth.
If you do mostly web surfing, email, or occasional downloading of media you will not notice any difference between the 2 and if anything maybe even think the DSL is faster even though Mediacom advertises as being faster in reality they are about the same if not slightly slower than Qwest in some aspects. I've had both and I have not noticed any decrease in performance of my internet since switching to Qwest and in fact it's been much more reliable than Mediacom.