You will be able to see all files...but you won't be able to run Windows or any of the programs on that disk...or access any of the files under the Docs/Settings group.
You can overcome this routine aspect (inability to access Docs/Settings group) by taking ownership of the files.
How to take ownership of a file or folder in Windows XP - http://support.microsoft.com/kb/308421
If the drives are PATA/IDE...you must be sure that you change the jumper setting to agree with the setting on the second system. If the second system boot hard drive is set to Master, then you must change the jumper setting on the moved hard drive to Slave. If the second system hard drive is set to Cable Select, change the hard drive setting on the moved drive to Cable Select.
If they are SATA drives...no jumpers are involved.