Hi and welcome to ExTS
Your original drive is a 2.5 inch IDE.
There are basically 2 types. IDE ( PATA ) and the more recent SATA.
The connections are totally different.
Obviously you will need a compatible drive.
Desktop drives are 3.5 inch.
Also ......
There are 2 different speeds available. 5,400 r/m and 7,200 r/m
The 7,200 transfers data considerably faster.
So - you want a 2.5 inch IDE 7,200 r/m drive.
I would suggest that you look at something a little bigger than 160GB - but this is obviously your choice.
Hope this helps :)
EDIT
Our last posts crossed - 1 minute apart.