1. Yes it's a good board! That is a very general question so I can't elaborate any more, but I've got it and had no problems at all!
2. If you already got one isn't it a little late asking if it's any good?
3. You should buy a sound card only if you thinks that the sound quality isn't enough for (it is for me), Since you've got the board it really is up to you to decide if the on-board sound is good enough!!!