Sorry for the double post but the site went down before I could edit the last one.
As far as can tell not all X300 based video cards can output component signals with a simple adapter. This functionality is based on the card manufacturer not just the chipset. See these specs:http://ati.amd.com/products/radeonx300/specs.html
You should check with the card manufacture to see if they have a simple DVI or other adapter based solution to your problem.
If all else fails you could try the ATI adapter. I doubt it will work as the X300 chipset isn’t listed as supported but it might work, or ATI could give you another option.http://ati.amd.com/products/hdtvadapter/faq.html#2
One thing I noticed is that ATI says that with their adapter you can only run one display. So if your card’s manufacturer says that they have an adapter make sure it still allows another monitor to run at the same time or you loose the advantage of running two monitors. If this is the case you would still have to get one of those expensive VGA to component converters or better yet just get a new video card.
Another possibility, if your AV receiver will take a DVI input and convert it to component output you may already have a converter.