Well, if it's rusty, but no rust holes, the very best thing you could do right now, is to clean it up as much as you can. Sandblasting, sandpaper, however you can remove the rust. Take it down to bare metal, and spray it with rust-oleum paint. Then buy a can of undercoating, and undercoat any problem areas. Also, if the rust is fairly bad, i would invest in some torsion braces. You can get them from
http://turbinetech.ca . The owner of that store is one of our best members on Teamswift.net. The strut tower braces won't fit your newer metro, but the underbody brace will. It will prevent the frame from flexing, and prevent cracking around the weaker rusted areas.
http://www.turbinetech.ca/Products_s...ionENlayer.htm