which specific interface do you have? The download page for that laptop shows the intel 1000 or 6200?
6200 says it can do 5ghzhttp://www.intel.com.../6200/index.htm
1000 I think is only 2.4, but quick google did not actually verify that - but since it jumped right out that 6200 does support both while could not actually find statement of such for the 1000, I have to assume it doesn't
Since your saying your not seeing 5ghz? I have to assume you have the 1000. Actual details of what wireless card would allow us to for sure verify what it supports or doesn't support.