It's not just the text on the page that's smaller; it's everything on the page.
Are you talking about a web page opened in Internet Explorer or another browser?
It may be that you accidentally zoomed out the browser. Press Ctrl + *
(press Ctrl, keep it pressing and then press *) for Internet Explorer 7 and 8. Press Ctrl + 0
for Firefox and Opera.
Are you seeing everything smaller including windows and other programs?
If everything is smaller then possibly your screen resolution is set a little higher than you usually had before. To change the screen resolution follow this excellent article by Microsoft : http://www.microsoft.com/windowsxp/using/s...resolution.mspx