Most modern PC's will have a Gigabit capable Network adapter in them, and it'll be set to Auto Negotiate by default, meaning they'll connect automagically to a 10Mb, 100Mb, or 1000Mb Switch.
One easy way might be to find such a PC and check the speed that it connects to the LAN at, which will tell you the speed (and duplex) of the port you're connecting from. You'll need to check that it's set to Autonegotiate first of course.
One common issue with speeds is the common speed/duplex mismatch issue. This will manifest itself particularly under fairly heavy load, and for this reason I'd strongly suggest manually setting the speed and duplex of any Server or Router connecting to the fastest supported speed and duplex combination, which would be in order of fastest to slowest 1000/Full, 1000/Half, 100/Full, 100/Half, 10/Full, 10/Half.
Just because the Switch is capable of Gigabit operation, it doesn't mean that the cabling is! If you're using old Cat3 or Cat5 cabling that a chair has been running over for years, don't expect to get 1000Mbit performance from it!
Hope you find something useful in my ramblings above!