I’ve been helping my friend Corrin build a Hello Kitty computer. Once it is complete, I’ll post pictures of the whole setup.
The keyboard:

It is hard to tell from this picture, but the keys have Japanese and English characters on them. It has a bunch of buttons for controlling media playback at the top.
Hello Kitty Keyboard at Amazon
The speakers:

You need to see these in person to realize just how cute they are. The computer isn’t all put together yet, so I haven’t been able to test the sound quality.
Hello Kitty Speakers at Amazon
The mouse:

The only Hello Kitty themed mice seemed like they would be awkward to use, so we picked this mouse instead. All of the clear parts glow white, and it looks really cool.
Glowing Pink Mouse on Amazon
The case:

There aren’t any Hello Kitty cases, but Raidmax makes this great looking pink case. We replaced the cheap power supply that came with it. The case itself seems really nice, with plenty of room inside. It has covers that go over your optical drives so you can use any color drive you want and still have it look pink. The picture looks a bit lighter than the case really is. It is actually closer to the color of the mouse, so everything matches pretty well.
Pink Case on Amazon
Decoration:

To make the case Hello Kitty themed, we’re considering using these stickers. They are designed for walls, but should look great on the case as well.
Hello Kitty Wall Stickers on Amazon
Once we get everything together, I’ll post pictures of the final product. Right now we’re waiting on a replacement motherboard. The one we bought was dead on arrival.