I would say to make sure it can run flash, though.
Dd1 (y1 since yesterday) uses reading eggs and the cbeebies website, although she used them a lot more before she started school. She also plays maths and literacy games on my iPad and we watch science videos on YouTube on our TiVo bx. I am starting to introduce 2yo dd2 to computers too now, but she can't yet manage a mouse. She does play on the iPad though, surrounded by cushions and with me holding it, lol.
To me, they need to learn mouse and keyboard skills alongside pen skills. ATM, dd1 is fairly slow with both, but she will learn. Dd2 is starting to copy shapes with a pen, so it is time to learn how to use a mouse. Plus it is a lot easier to just press a button than form a letter.
I spent most of school being told off for bad handwriting (books ripped up in front of the class etc - I'm 27, so not that long ago) and the school IT was woefully inadequate. I know things have moved on since, but who really handwrites more than the odd list as an adult?
Still, netbooks are pretty slow and restrictive - another vote for his own keyboard for your laptop. We are fairly poor too (but geeky, so we spend a disproportionate amount of money on gadgets) and a netbook for his own use doesn't seem like an effective use of cash, when you could spend the same on accessories for him to use with your laptop (a printer is brill, get the mega cheap ink off amazon)
School don't request use of a computer at home, but they also don't request use of a dictionary or encyclopaedia, so