As for your sound driver.. you say Windows 7 fails to install it.. well are you trying to install a driver through Windows Update? or manually? If your trying through Windows Update than I'd suggest searching for the latest Windows Vista driver for your sound card (if there's not a Windows 7 specific driver out for it currently) and manually installing it... That should work a little better for ya..
As for it not picking up the second partition on your HDD... is the partition it's not picking up the one that you have Windows XP installed on? Because if it is, then that's perfectly normal.. Win 7 doesn't "see" a partition that Windows XP is installed on.. I'm not 100% sure as to why that is.. but that's normal. It doesn't mean that the partition is no longer there, it just doesn't "see" it.. It is a little confusing though because if you boot into Windows XP you CAN in fact see the partition that Win 7 is installed on.. so I can understand your confusion there.. but not to worry.. it's normal..