While not scientific and only a good guideline, you can use DU Meter and transfer a very large file. I did this and DU Meter registered a solid 23 Mb per second. I had to use a 1Gb file to get an accurate measurement with two computers hooked up with a Cat5E crossover cable using all 4 pairs.
Download NetCPS to two computers which have gig network cards. NetCPS doesn't factor in harddrive speeds and stuff like that, just NIC and router/switch speeds, so you'll get a pretty accurate reading of what your network is capable of. That said, transferring an actual file will more then likely be slower due to the harddrive and processing needed.
I use Crofts Software Fire Monitor to keep an eye on the inbound and outbound traffic speeds on my nic's... nice little tool to use..
Here is the deal.. 1000 is ten times more than 100... so its going to be faster, and thats what you wanted... faster.. You are not going to tell a diffrence in your internet speed at all.. but if your moving a 7GB file from PC1 to PC2.. yeah.. you will see some improvement.. but like some one else said.. you have disk queue to deal with as well as OS overhead... the switch fabric of a netgear is nothing like that of cisco or 3com.. so don't expect those blazing data center transfer rates... on the other hand don't be bumbed out that you only got a 30% increase in transfer rate, its 30% more than you had before.