Personaly I’d stay away from DELL.
Anyone in my family or friends have had all kinds of issues. Theses ranged from drive crashes to corrupt operating systems and I have had to restore from scratch.
I have had good luck with Gateway, Acer, HP, Compaq, Toshiba ans Sony
Other than that I’d say an i5 minimum processor, memory would be based on the software you plan on using. If you plan on using a purchased package for multi-media, I’d boost it by another 50% over the recomended memory amount.
If performance is an issue you may want to go with a dedicated video card (512mb) and depending on how involved the graphics or video editing a dual video card PC.
Just my 2 cents
Also a large hard drive, I’s say a 500 gig minimum. You can check out some on line stores that have systems that would fit your needs with 6gig RAM, 1 Terabyte HD and Windows7 for about $600 (US)