You have to be a little careful as your C: partition may be redundant - except for Boot.ini.
You will probably find that the old C: partion is still the active one and boot.ini is directing you to the H: partition.
The other issue is that, unlike Win98, drives are not lettered dynamically at start up but are allocated within the XP system.
You can use Disk management to reassign letters but it is difficult for the primary partition and can lead to problems. There are ways but they are messy.