Connect PC to HDTV using RCA Composite Cables
"Can I connect my PC VGA video out to my HDTV much like I do my DVD player using the Yellow, Red, and White RCA jacks?"
While you certainly could get a VGA to composite video adapter, to connect your PC to HDTV, I'm not really certain why you'd want to. Most computer video cards support HD video resolutions like 1280x720 and 1920x1080 using either component connections (the red, blue, and green RCA cables), HDMI, DVI, or VGA. At best the yellow RCA connection you make on the composite video-in will be 480p or 640x480, which is the equivalent of many cell phone screen resolutions. There are probably several better choices for your connection instead.
Buy an HDMI Switch
If the reason for opting to connect your PC to HDTV via composite is because that's the only open port on your HDTV, you may want to consider getting a signal switch for your home theater setup, rather than massively degrading the image from your PC. Buying a 5-port HDMI switch is reasonably inexpensive and video quality from your computer VGA port to HDMI will look magnitudes better than attempting to connect VGA to composite.
Use VGA to Component Adapter
Conecting your PC to HDTV via component is a better option than using composite if the option is available. Just be sure not to be tempted by the low price of cables promising a VGA to component connection, because a VGA to component cable won't work for connecting your PC to HDTV. Instead you need a converter box like the Startech VGA to Component (YPbPr) Video Converter available on Amazon. VGA video signal information isn't directly compatible with a television component signal, which is why the coverter box is required. In most cases if your computer video card supports at least 1024x768, the converter box will output 1280x720 video.
I would still recommend going with a VGA to HDMI or more ideally DVI to HDMI, if you computer doesn't include an HDMI out. In either of the two scenarios I suggest here, you will also need audio cables to go from your computer sound card to the HDTV for audio output.