If your eyesight isn't what it used to be, you may want to increase the size of the sheet tabs displayed in your Excel workbooks.
This parameter is determined by a Windows system-wide setting. To change it, select Start, Settings, Control Panel and double-click Display. In the Display Properties dialog box, click the Appearance tab, and choose Scrollbar from the Item list. Adjust the sheet tabs until they're the size you want. Be aware that this setting affects the scroll bars in ALL OF YOUR APPLICATIONS.