I'm just highlighting the range with my mouse and then tabbing through the cells.
Another way of doing something like that is with protection. If you select the range you want to work in and right click and select Format Cells. Go to the Protection tab and uncheck Locked and click OK. Then go to protection (Alt +T, P, P on the keyboard. I can't find it on the 2007 ribbon. Stupid ribbon! In 2003 and before it was on Tools | Protection | Protect Worksheet) and click OK. When you're done you go back and turn off protection and select the cells, Right click and select Format Cells | Protection Tab and check Locked and click OK.