Vista

I try to keep the non-political posts confined to the weekend, but my question here is brief. I do some fairly high-end Photoshop work on a somewhat antiquated system -- a single core Athlon and 1.5 gigs of RAM. Yeah, I should upgrade to a double-core system with at least two gigs of RAM, but bucks are tight. I've read that installing Vista will slow Photoshop performance 13%-25% on a system like mine. If that's so, why on earth would I want to pay for such a thing?