HP doesn't show a VL8/400 but it did have a VL400 or a VL6/800 So I will assume a VL400
It was easy enough ...
I went to
http://welcome.hp.com/country/us/en/support.html SAVE that URL!
Select the "Download drivers and software"
Enter your model # in the box
click on the little double-arrow to the right
Select Microsoft windows98
And you'll have a whole page of drivers,etc.
get your video drivers, audio drivers, modem drivers, etc.
Since you had to reformat everyhting, I would go ahead and download the latest drivers they have for all of your hardware.
Do not download a CMOS update unless you have experience doing this - it can totally/permanently crash your system if an error is made.