|All hard drive manufacturers have FREE software to migrate to a newer, bigger drive.|
Problems can arise is you are migrating from an IDE drive to a SATA or if the BIOS is NOT 48 bit LBA compliant and you migrate to a drive larger than 127GB.
Otherwise these programs usually work. Sometimes there can be problems if one or both of the drives have multiple partitions.
If the drives are of different brands the software from either brand SHOULD work. I would recommend using the software from the new drive manfacturer.
If going from IDE to SATA you may get by if you install the SATA controllers BEFORE cloning.
One other issue can be motherboards that only support SATA I drives if you install a SATA II drive.
You may need to throttle the drive speed by means of a jumper on the drive. Not all SATA II drives have such a jumper though.
Why not leave the old drive in place and just add the second drive for storage and programs?
I have machines running with 3 hard drives installed.