*.PIF

see link below.

A .pif file is used to start a program written for MS-DOS within Windows, and can also be used to configure a unique environment for individual MS-DOS-based programs that run in MS-DOS mode.

http://support.microsoft.com/support/kb/articles/q188/1/57.asp

What a pif file enables you to do is to run a program that was orginally written in MS-Dos mode in the windows enviroment.

I have attached an link to Microsoft which will explain more all you need to do is to copy and paste the link into you internet explorer bar

http://support.microsoft.com/support/kb/articles/Q188/1/57.ASP?LN=EN-US&SD=gn&FR=0&qry=what%20is%20a%20pif%20file&rnk=7&src=DHCS_MSPSS_gn_SRCH&SPR=W98

Cheers

Martin