I am guessing that HDMI will have to best effect, however is it worth it to go buy a 40 dollar cable when I already have a VGA and a DVI cable? If it will make the monitor stand out, then 40 dollars is well worth it, but if it's hard to tell the difference then I don't want to bother with it. Anyone have any input on the big differences between the three?
There isn't a really good reason to buy a $40 cable for a short length (6 feet or under). As long as the HDMI cable is 1.3 compliant, it will work just fine. My cable is worth $12, and it looks just as good as the $60 cable I foolishly bought for my TV.
There have been some studies made by impartial engineers (I get the trade publications in electronics) that have shown that the bandwidth in an HDMI cable is pretty much the same, no matter the cost. Basically, your eye can't tell the difference.
The only real good reason to buy an expensive cable is if you need to run a long length of it, say more than 12 to 15 feet. A more expensive cable usually has better shielding that rejects interference that affects the picture. In that case, it's a good idea to spend a bit more, but for standard PC to monitor cable lengths you don't need to break the bank. Just make sure that it meets the 1.3 standard for HDMI and you're good to go.
DVI might be a better way to go, anyway. I found that running my monitor with an HDMI cable taxed the video cards heavily. They run at full speed all the time with HDMI, but downclock under minimum load with DVI. Not sure if it's a driver issue, but ATI's latest drivers have been a little flaky...