The keyboard you're typing on is probably gross as hell, and it isn't doing any favors for your posture, either. Consider replacing it with Microsoft's stalwart ergonomic split keyboard, which is on sale for $30 from Amazon at the moment.
Microsoft's been making ergonomic keyboards in one version or another since the 90s, but they seem to have hit the sweet spot with the Microsoft Natural Ergonomic 4000, which hasn't changed since 2005. One of its most notable features is that it includes the full PgUp cluster—other (higher-end) Microsoft ergonomic keyboards omit those keys. I've typed on one, and it certainly feels like a solid peripheral, unlike some cheap keyboards and mice. Blogger Jeff Atwood gave it a great review back when it came out.