I bought one of those usb adapters that has video and stereo audio input to convert my old movies to MP4's. Video quality isnt the best, but VHS was never as sharp as modern videos anyways and magnetic VHS tapes that are 25+ years old like Police Academy are going to show their age when played with loss of colors etc.
To be legal you just need to retain the original VHS tapes... my wife wanted to throw them away to save space, but legally you have to still own them or it could be seen as illegal since someone could have picked the VHS tapes out of the dump in which your in violation for duplication. I am using video on fair use basis as I still have originals. If originals ever get tossed the MP4's would have to be deleted.