X-Gamer is the same Sound card as the Platinum. The platinum comes bundled with a live drive, but the actual card is no different.
The Philips AE is the best sound card on the market in my opinion. From everything I've heard it has great drivers in Win2000, and I've used my friends in Win98, very versatile, excellent quality, it will do everything the platinum can do and then some for 1/2 the price. Unless you absolute need optical out for some reason I can't see any reason to buy any card other than the AE (the AE has full digital I/O, just in RCA format, not Optical).