I have additional information for you. I was working on someone else's computer this morning and it had a Logitech mouse (M705, don't know if still in current production, but it had programmable buttons.) So, I remembered this discussion and I checked with its control panel (SetPoint settings.) I saw speed controls for horizontal scroll (items #6 and 7 under "my mouse", left and right scroll, adjustable individually.) Which means that also Logitech mice can scroll horizontally. So, you probably don't even have to buy a new Microsoft touch mouse.
Desktop: i7 3770k, 32 GB RAM, nVidia GTX680, 3 monitors, 256 GB SSD (OS), 2 TB SATA III (audio), 3 TB SATA III (sample libraries), 3x 3 TB USB 3.0 (backup/archives), RME UFX, Win 8 Pro x64, Cubase 7, Sonar X3, Vienna Ensemble Pro 5.
Slaves: 2x i7 2700k, 16 GB RAM, 256 GB SSD, 3 TB SATA III, Win 8 Pro x64, Vienna Ensemble Pro 5.
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