Forgive the possibly noobish question, but we recently redesigned our site and on an SEO friend's suggestion ran it through the W3C markup validator: The home page produces 30 errors, and I don't really know how to interpret the output (pasted below). How critical are these errors? And can anyone explain in noob-friendly terms in what ways are they are hurting our they affect performance? SEO-friendliness? Something else? In short I just want to know what priority to assign fixing them, since our time/budget are limited.

Was going to paste the W3C error output here, but it didn't format well, but you can see it here: