I'm using a Creative Audigy Platinum Version 1, which was the first of the line. Noise wise it's pretty good but the V1 chipset forced sample rate compromises which made the card of limited use to serious users; the drivers are also total garbage for XP and I'm using a set of 3rd party drivers instead.

But this is a four year old piece of kit.

As far as I know the new stuff does not restrict sample rate in the same way (but I'd still check the small print) and the drivers are much better. I would expect any of the new high-end Creative soundcards to be significantly better quality than your on-board chipset (even if high-definition it says nothing about the noise; there's little point in 24 bits worth of A-D if the lower 8 bits worth of resolution finds itself recording white noise due to electrical interference or lower quality preceding audio processing).

If you are really serious then try to get the A/D and D/A converters out of the PC and into an external converter box; do the current higher-end Creative sound cards still come with an external interface unit?