Can my pc handle windows 7 or just windows vista?

Windows 7, or XP, not Vista. Upgrade to 4 gigs memory, and get AT LEAST a 160 gig hard drive. I still run XP, and have XP Pro on my laptop. I had a free upgrade to Vista, will not touch it, and I will use XP until I need a new computer, then will buy a purpose-built Win7 machine.