It is really better compared to a regular HDD but state your budget first because some of them priced to give people heart attack..

Gigabyte using another controller on another GSATAII port other port are using Intel controller.
Try go to Gigabyte websites download its drivers for the SATA drivers.
all the while u didn't use that GSATAII port rite.
Also possible u didn't format the drive initially so cannot see in windows.

Fresh Windows install Win7 in SSD where connected to the GSATA port also need that Gigabyte driver, make sure copy the driver files into a Flash Drive 1st before install Win7, otherwise Win7 cannot see it initially.
If plug into Intel Controller ports, Win7 should detect it.

U can boot Win7 DVD & format there also can, once in Win7 detect ur HDD, if 1st it can see, then no need GSATAII Drivers,
if cannot see, then select load drivers & point to the Flash Drive with GSATAII drivers in there, once loaded, Win7 Setup sure can see.
Usually I will load the latest drivers Gigabyte provide no matter Win7 setup see it or not, cause I want newer drivers.

For about U can't format in current Win7. Actually you can format it too, u just need load the same drivers within windows 7.
Once the Drivers is loaded, Win7 can see the Unallocated Space from the Disk Management. U know how access Disk Management right ?
In case not, right click My Computer, select MANAGE, then left side select "Disk Management".

If I not wrong, the Gigabyte SATAII Drivers is using JMICRON J36x Chipset, usually I go straight to JMICRON websites download it latest drivers one.
Sometimes gigabyte also didn't update it.

Let us know results okay ?