One option is to move all the data off the 130GB drive, then delete that partition. You can then expand the 70GC primary partition to include the unused space. I do not believe Partition Magic will work (at least not as of the version I had last) for this particular purpose, with Windows Server 2003 and a primary/boot partition involved, I used DiskPart to expand that partition out to use the extra space. Remember to move all data from the second partition first, or you’ll lose it when the partition is deleted!
I recommend leaving it partition breakdown as is. If you put everything as a single drive and users max out what’s available, the whole system crashes. I would rebuild the server with 30GB OS C Drive and 170GB Data D Drive. You should then enable quotas on the D drive to control that volume. You may want to see if you can add more drives to this server cause 170GB will get filled up quickly.