Can I make my C: partition bigger by taking space from D:?

I would suggest simply deleting the second partition and increasing the size of the first into the new space.

That works if you don't mind losing any data on that second partition.

Though pricy, I'd definitely recomment Partition Magic. It's done the job for me.

if memory serves, isn't there a way to change partition sizes in the "disk management" under the "computer management" in the administrative tools?? I could swear I've done that before, if not, nevermind...lol

I believe that's a destructive resize. Meaning that the data on the partitions is lost. These utilities do it while preserving your data.

I have used Partition Magic for a long time across many releases. However, since the vendor (PowerQuest) was purchased by Symantec, the product seems to have been abandoned. There have been no updates for a very long time. And its not problem-free (not that any software is). See
http://www.computergripes.com/PartitionMagic.html

There are partition products that have free trials :) And if you will only use it once every couple years....then stick to the free trials...It's free and works great!

If I delete the empty and unused "d" partition, will the "C" drive automatically absorb the free disk space, or will the WinXP program ASK me if I want the "C" drive size increased?

Neither. You need to use a partition resizing program.

I have only 1 partition in my laptop c:
how can I divide into various partitions.