Couple of things to think about. If you want to record onto your laptop, you'll need a pre amplifier, which takes the faint signal from a mic and boosts it to a level ("line level") that the line input on your laptop can recognise. The laptop will also have a mic input with its own little pre-amp but it will be horrible. There are hundreds to choose from (search for preamps on this bbs and you won't emerge for weeks

). However you might want to do some more cost effective buying and get a USB audio interface - a basic one will not only give you 2 preamp channels but will also take care of the Analgue/Digital (and vice versa) conversion, replacing your laptop's soundcard with a higher quality process.
You mentioned a MIDI connector. You'll need one of you want to send MIDI instructions from your keyboard to Cubase, to trigger sounds from a software synthesiser (Cubase comes with one plus a drum machine). On the other hand if you are just recording the audio produced by your keyboard synth you just plug it straight into the line input of your laptop, with a suitable adapter for a 1/8" stereo jack, and record it in Cubase.
Of course, if you have a mic and a synth, you might want to get a little mixer so you don't have to keep unplugging things. And then there's monitoring - you'll need some good monitors to listen to your mixes on. Search for the monitor discussions here and I guarantee your computer will blow up so you'll need a new one of those as well

And then after a bit, you'll feel that the room you're recording and mixing in is emphasising certain frequencies, so you'll want to treat it. Then you'll want to experiment with a different mic. And you'll wonder if some of the software synthesisers you can get wouldn't sound better than your hardware keyboard. Then you'l want a better way of doing the drums. Then your friend will come round with a guitar and that will need whole new recording thought process.
Welcome to the slippery slope to HELL!!!!!!!!
