Congratulations on the new keyboard! I think you'll find the PSR-E463 to be very versatile for the price. And the jump from computer graphics to music may not be quite so far as you might think, as there is quite a bit of math hidden in music theory. A couple examples...
1. Computer programming makes use of the binary system, where numbers are expressed using only 0's and 1's. With a binary number, each successive digit, going from right to left, has a value that is the next greater power of two. So, for digits that are a 1 (not a 0), when converting it to decimal, the right most digit has a value of 1, then the next digit to the left has a value of 2, then the next digit has a value of 4, then the next has a value of 8, then 16, then 32, and so on. Well, with keyboard organs, the octaves are often expressed as "footages", relating to approximately how tall a pipe would be on a pipe organ to make a particular pitch, and these are also expressed as powers of two for octaves, where a 1 foot setting is usually the highest pitch, a 2 foot setting is an octave lower, then a 4 foot setting is another octave lower, and an 8 foot setting is yet another octave lower, and so on.
2. The construction of scales and the musical keys follow a certain mathematical progression. Notes of a scale are a certain number of keys apart, depending on the type of scale, such as major or minor. And with musical keys, each addition of a sharp or a flat changes the key by a value of a fifth. So, with major keys, the key of C has no sharps or flats, but the key of G has one sharp (G is a fifth above C). Go up another fifth, to the key of D, and that is two sharps, and so on. Going the other way, from C, go down a fifth, and you have the key of F, which is one flat. Go down another fifth, to the key of Bb, and you have two flats, and so on.
And yes, while the Casio does have some impressive features and good sound, it is buried under a complex array of menus. And I saw a CTX-5000 in a music store last week -- their top line portable keyboard -- and the feel of the keyboard was very "plasticky", where I could hear that kind of plastic-tinny sound coming from the keys itself as I tried it out. Maybe it was just a well-worn display model, but I definitely prefer the Yamaha key feel.
Feel free to ask any questions about either your keyboard or music theory on this site!