Installed SATA drive but its not picking it up

[l3ights]

i had an external SATA drive, which i took apart and installed into my comp, connected power lead and sata lead to motherboard, turn on computer and went to my computer to see if it picked it up and it didn't, went to control panel and then device manager and it shows the drive is there, i'm running on vista.

so it shows there but how do i use it??

Do i have to format it 1st or not?

I know there is stuff on the drive, but not sure what is on there,

Any idea's??

[l3ights]

i've sorted it, only thing is now that i have noticed is that it is a 400GB drive but when i went into Disk management and allocated the drive and formatted it, but i noticed it said there was 372GB on it, what happened to the other 28 GB,

Does anyone know what i can do to find out about this?

[TazUk]

Drive manufacturers measure in units of a 1000, i.e. 1 kilobyte = 1000 bytes, whereas Windows measures in units of 1024, so there's always a discrepancy from what the drives capacity is as advertised by the manufacturer and what it is when measured in Windows.

More info