I have a couple of hard drives from an older desktop computer that I wanted to put in my new desktop to use as backup drives.  However, when I opened up the new computer (a Dell Inspiron 530) I noticed that the cords that connect to the hard drives are much different.  On the old computer (a Dell Dimension 8200), the hard drives were connected by wide flat ribbon like cords.  On the new Inspiron, the cord is much smaller.  

Can I still use the old hard drives with the new computer or do I need to somehow convert them to external drives and connect them via a USB or serial port or something like that?

Thanks!

Are the new drives connected with a wide IDE connector or a smaller SATA connector?
Some IDE cables have been made as round cables, but still have the same connectors at each end. The SATA cables have smaller connectors.
If you have SATA drives, do you see any slots for IDE connectors on the motherboard?
If so, you can connect your old drives with your old cables.

Even if you have Sata drive connectors your CDRom might have an IDE connector that you might be able to use to connect one of these drives. Just make sure the master/slave jumpers are connected properly.