The easiest thing to do will be to put both Hard Drives into your PC.
One drive needs to be set as a master and one as a slave, via jumpers that are usually on the back of the HDD between the power & idc connectors.
Do a Google of the manufacturer/model no of each drive to get the jumper settings (if these are not on a sticker on the drive itself).
Some destructions for setting jumoers can be found here:
If you don't want to re-install XP and all our applications, you can use free software to clone the small HDD onto the larger HDD. I have used XXCLONE to do just this.
When you have done this, just swap the master slave designations of the two drives.