Maybe it's a byproduct of the phosphorescent Disney babysitter that raised us, but it's near impossible to look at Sony's Walkman players and not think whimsically of Mickey Mouse. An unfortunate emotional response to otherwise very serious competitors for your portable audio dollar. Joining the S-series are the new S640 and S740 Walkmen officially unveiled today in Japan. Both feature 2-inch LCDs, 720x480 TV-out, and the same quality MDR-EX300SL earbuds shipping with the better-speced A840. The S740 (8GB/16GB/32GB) brings noise cancellation while the S640 (8GB/16GB) saddles your brain with ambient noise filtration. Shipping later this month in prices ranging