The absolute simplest (not necessarily the best or the cheapest) way is to buy a stand-alone "entertainment system" DVD recorder with a built-in tape player (which may or may not also record tapes). With most of these, you put in the VHS tape and a blank recordable DVD and press one button, come back [the length of the tape] later and you are done.
The downside is that this may be expensive, and it allows only rudimentary editing (or very possibly none at all).
If you want to use a PC, you need a hardware capture device that can take the video output of a VHS tape player (VCR or just player) and convert into USB or Firewire. You also need software that can capture the output of the conversion device onto the hard drive, and DVD authoring software to use those files to make a video DVD. All of these pieces can be bought together or separately, and the level of complexity and quality can vary all over the map.
I don't want to suggest a specific product, but Pinnacle, Roxio and many other vendors offer consumer level software bundled with a compatible hardware device that can do the whole job. Alternatively, you may want to just use a capture device and use some more advanced software that will let you do extensive editing with transitions and special effects (something like the more advanced pinnacle products or Premiere Elements). Finally, the ultimate high-end software is full version Adobe Premiere, but it's price (over $500) is out of the reach of most consumers.
For most people however, either the stand-alone DVD recorder or a fully bundled consumer level package including both hardware and software (for less than $100) will probably be the best solution unless you want to do more than "just" convert the media, e.g. unless you want to do extensive editing.