If you have 11Mbps speed available, that's the maximum speed of the old 802.11b standard. While the theoretical speed is 11Mbps (that's megabits per second), your actual throughput is closer to what Karen mentioned.
Newer wifi standards are 802.11g and the still pending 802.11n standard. 802.11g has a theoretical limit of 54Mbps with normal throughput around 18-25Mbps. The newest standard promises breakthrough speed of perhaps 300-400Mbps, but the standard is still in the ratification process. So out in the market, you'll see Pre-N routers that are based on the draft standard.
If you're transferring files around your local network, 802.11b is rather poky with wired networks offering either 200Mbps (full-duplex 100BaseTX) or even gigabit ethernet (as you would expect 1,000Mbps or 2,000Mbps full-duplex). If you want to do this, you might prefer 802.11g instead, which costs only a slight bit more than 802.11b hardware to get you 5-10X more speed. If, as you imply, you don't actually own the wifi hardware and only have access to it, you don't have a choice to upgrade to 802.11g. But all is not lost.
If you never transfer files between your computers and only surf the web, 802.11b is adequate since the speed of your connection between your computer and the router only has to match your Internet connection speed. I have one of the fastest available cable modem connections that goes around 8Mbps with bursts of up to 12Mbps through Comcast Cable (for inbound connections with 768Kbps for outbound). But most cable modem speeds are between 1Mbps and 3Mbps. The odds are, your wireless speeds are faster or as fast as your Internet speed anyway.
DSL is even slower than cable unless you have Bill Gates' wallet. Dialup is glacial when compared with any wireless standard.
And also as Karen mentioned, there are websites like dslreports or cnet that have the ability to test how fast your Internet connection is to see if your wifi will slow you down. Most likely it won't.
