The chair along with the desk should be comfortable with sufficient armrest along with it. The fabric of the chair should be easy to maintain and use.
The Computer is used for work, social networking, watching movies, listening songs and many more, but the objective of the desk should be o provide high comfort level to the user.
Always measure the area where you have decided to keep the desk. Usually it is available in standard sizes, but in small apartments you have limited space availability options.
You can buy it easily from furniture shops or exclusive shops which sell computer related furniture. There are many sellers available on the internet marker also from where you can grab the deal at reasonable prices. If you have any specific requirements and thinking of getting the desk customized you can check the designs or styles available on the web or magazines and get it tailor made from an experienced carpenter.