The lines before windows loads is pretty much an indication that the card is bad. If the video has artifacts (the lines, etc) before the driver loads, then it most likely is the card. You could use ATITool (which is more an overclocking utility, but should still work) to scan for the artifacts, but be careful not to mess with the GPU core settings. You can find the download here:
http://www.techpowerup.com/atitool/