In the Old Town, you find many shops which sell all kinds of clothes, shoes and there is also a big CD-store called WOM World of Music on the second floor of the fancy clothes store called KULT.
In the area of Shadowstrasse, you find the huge department stores like Kaufhof and Karstadt where you can buy anything from food or clothes and stationary to watches. There is also Dusseldorf's largest photo equipment store called FOTO KOCH in case you run out of film. If you want to buy clothes you can also go to C&A or Peek&Cloppenburg or to one of the many fashion boutiques in this area.
In Königsalle the largest CD-store SATURN has just opened (2000) a new store which is definitely worth a visit. CD's are about 15 US$ in Germany which is among the cheapest prices in Europe.
Please note that shops in Germany are open only until 6.30 p.m. except for Thursdays when they are open until 8.00 p.m. On Saturdays, only the bigger shops are open until 4.00 p.m. and on Sundays all the shops are closed.