Additional hard drives not recognized on veriton

Hi , I have set up a verton to test differnet hard drives , however when I connect different hard drives they power up but not recognised by the computer ? I check in Bios but dont see them either yet the hard drives are Good ?

Also I would like to speed this machine up . I appreciate its an older machine , but to me its exceptiuonally slow

can anyone give me some pointers please ... I am running windows 7 ultimate and have to meg of RAM also I not the hard drive has two partions . one for the operating system and also one for data ... this shows as two hard drives when I look ( C and D ) ... Is this correct ? If anyone would like to give me some pointers and share their experience , it would be appreciated