hi. i using iphone 3g too. but i'm using mac. but maybe i can answer your question.
1) at itune8 you can choose what type of song you can sync to iphone. check it out after you plug you iphone to your computer.
2) your itune8 should be the first versionwhich come out on 12 Sept and i believe you using window. there is another update verions of itune 8 which already solve this problem but you have to uninstall your itune8 completely first then download and install it again.