The simplest way is to plug a VHS player into a DVD recorder. The quality off VHS is not great to begin with. If you use the Long Play mode (4-6hrs per disk) on the DVD recorder to squeeze as much footage onto one disk as possible you will make it worse.
If you use the one or two hour per disk options you will get far better results. At the expense of needing more disks. But since they are so cheap nowadays is that really such a problem.
And the machine used to record the DVDs can make a difference. If you use some cheapo thing from Argos or a Currys or Comet own brand unit that costs about the same as a Big Mac then you are likely to get poorer results than using a Sony or Panasonic recorder.
You can get video capture devices for PCs such as this
http://www.pinnaclesys.com/PublicSit...2BPlatinum.htm
This plugs into the PC via USB and you plug the VCR into the box on the end of the lead. You then play the video and it converts it into a digital format on the PC hard drive. Using the software supplied with the device you can do some basic editing on the footage and then burn it to DVD. Assuming the PC has a DVD burner obviously.
But you may not actually make any difference to the quality of the result. And often the biggest pain in the wotsits using a PC is getting the whole lot to work. Plus the time it takes. If you have a DVD recorder and need to copy one hour of VHS tape it takes one hour (plus a few seconds to press the buttons on the remotes) Do it by PC and you need one hour to capture the video to the PC and maybe as much as another hour, or even longer to burn it to disk.
But if you already have a VHS and a DVD recorder that is all you need. Just set up the DVD recorder correctly.