new harddisk

[Ayman Altounji]

I wanne put a new harddrive in my computer, one of 20 Gb...the first problem, the computer thinks that it is one of 8Gb....
I clone the 2 harddisks, so the data is the same...and now i put the new one as master, and the pc won't startup, i tried everythin...nothing works, i can start it up with the a startup disk, but that's all, I won't try the recovery disk, because, I don't wanne rid of my existing data...

Can you help me? Please send a mail back
Regards