This 5Mb file contains the Win98 driver files
sn980017.zip (0.59Mb) [PCA 300/600PS scanner software upgrade. Philips Scan Module version before 2.48 cannot work under Windows 98.]
and also the files
sm248_1.zip (1.06Mb) sm248_2.zip (1.13Mb) sm248_3.zip (1.19Mb) sm248_4.zip (1.37Mb) [Scan Module driver v2.48 for Windows 98 and problem solving - disks 1,2,3,4]
Note Philips also offers drivers for the PCA600PS. Yet, most of the immense philips-website is not bookmarkable, so you are forced to search your way over and over again. try the "link" below for a start -)
For Win3.1x, win95, WinNT and the TWAIN quick panel search for the 300sm1-4.zip file (7Mb). Let's make better things!