I was planning to get studio monitors, but since my current setup has a tabletop computer (=noise) I thought there is no point to get expensive monitors yet. So I was digging through my stuff and found these.
Creative Gigaworks HD50. When I bought these they sounded bad and I threw them away. Now it's different, because making music with headphones only is annoying, even with my "studio" headphones (AKG 272). As an physical object they have weight and it's like having a helmet on your head all the time.
However I was able to improve the sound quality using a mixer. It's a good idea to get one, because computers don't seem to have good amplifiers and using outputs from computer with thin cable (one that came with Creative) is sure to add noise.
I have Alesis MultiMix 4 as mixer, placed on top of my computer. With good quality 6,5mm (thicker cables usually means less noise) Cordial cables run from main out and then using a Cordial 6,5mm mono to 3,5mm stereo converter piece (you can see it in first picture) the sound quality was improved. MultiMix is one of the cheapest USB mixers, but in comparison it destroys Acer's internal amplifier.
The cool thing is that I can adjust the overall volume from the mixer which is faster than adjusting from computer. And I can plug in headphones with separate headphone volume level so I can check out stuff if I need to hear something without too much noise from the computer.
This studio isn't really ideal, because there is no laptop computer (less noise) and I have to set up my midi keyboard in place of computer keyboard. It could be better to have a dedicated studio with everything set up ready, but I really have to complete my first song before I can start dreaming about that.