Will have to do some more looking for the "Micro CCID" device. The SM Bus device is the chipset. Looks like it's listed under the "All Drivers" tab on the Dell drivers site.
Go back to the Del Driver site, and click on the "All files for Latitude D620 (77 files)" tab. Find "Chipset" and expand that category; then next to the Intel-Driver link, click the Download link for that one and install that.