My parents bought my sister's first car with a credit card, and paid it off within a month just to get the bonus points!
Still, I only buy things if I have enough cash in the bank, but when your credit card company does that, you might as well buy it with credit and pay it off immediately.
New Rig: Intel Q6600 (2.7ghz), ASUS P5KC, 4GB DDR2-800, Palit 9600GT (1GB), Ultra X3 1KW (thanks LR!), Vista 64bit
Dell Rig: AMD Athlon X2 4000+ (2.1ghz), 2 GB DDR2 Ram, MSI 8800GT (512MB), Vista 32bit