Buy a Canon printer which has individual cartridges for each colour.
In my experience they waste less ink and are cheaper to run than any other make of printer.
More reliable too - which also helps to keep running costs down.
All new printers are compatible with Windows Vista & Windows 7
Yes, obviously they wouldn't recommend a brand they don't have in stock because they want you to buy one they've got!
But I can assure you, Canon printers are the best choice in my opinion - - I wouldn't buy any other brand.