First, I used CorelDRAW – at the vocational school where I studied multimedia, more correctly ‘Information Technologies and Multimedia Communication’ (crappy translation), in Portuguese ‘Tecnologias de Informação e Comunicação Multimédia’ – then I used Adobe Illustrator, then I got tired of it and looked for a cheap, lightweight alternative.
Inkscape…cheap enough (free), pretty lightweight and enough features for most small jobs.