Tim I was wrong with the resolution, you still nead a higher one.
Read this article from microsfot Knowledge Base, It talk about this problem and microsoft give a reference about a patch for this problem.

FIX: Report Print Preview Illegible Under Windows NT
Last reviewed: October 29, 1998
Article ID: Q156788




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The information in this article applies to:
Microsoft Visual FoxPro for Windows 3.0, 3.0b, 5.0, 5.0a
Microsoft FoxPro for Windows 2.6a


SYMPTOMS
When you use Print Preview to view a report in FoxPro running under Windows NT, the text in the report is difficult to read when using a low- resolution video driver.



RESOLUTION
One of the following methods can be used to resolve this problem:

The quality of the Print Preview appears to be directly related to the current video resolution. The higher the video resolution, the better the quality of the Print Preview. Typically, video resolutions of 1024x768 or higher yield satisfactory Print Preview quality.
-or-

Create two reports: one for Print Previews and one for printing. In the report for Print Preview, increase the font size so that it is readable in Print Preview mode. Note that there is less information placed on each page in Print Preview mode, which results in the Print Preview showing more pages than the report that prints to the printer.

STATUS
Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug is fixed for Visual FoxPro versions 5.x with the Visual Studio 97 Service Pack 2. If using a version of FoxPro or Visual FoxPro prior to 5.x, use the resolutions provided in this article.

For more information on the Visual Studio 97 Service Pack 2, please see the following article in the Microsoft Knowledge Base:


ARTICLE-ID: Q170365
TITLE : INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION


Steps to Reproduce Behavior
Your system should be running Windows NT 3.51 or higher, and should be configured with a video resolution of 640x480.


Create a new report, or open an existing report.

Preview the report. Note that the text in the report is illegible.