FWIW, although this has already been mentioned, it should be noted that DVI ports on video cards already carry the VGA signal in them, the pin-out is just different.. You can read up on DVI-I vs DVI-D on Wikipedia, but all you need for VGA is a DVI-I to VGA adapter and the video card will switch over automatically.

But don't do this. Use DVI.

(Video cards that have VGA ports on them physically vs. two DVI or one HDMI and one DVI tend to be lower-end cards, too.)

The "HDMI/DVI" port probably has an audio input associated with it for the DVI-only connections; even if you have an HDMI connector at both ends it still may be sending DVI-style data over the connection (depending on how goofy the handshaking of the TV is). But that's OK, your video will look fine. Hopefully the TV is smart enough to say "I can do 1366x768 natively in addition to accepting 1280x720 and 1920x1080". This is what it should do in theory, but practice is another thing entirely.