Display problem

I have a 5-year old system that is running with the original Radeon 9800 PRO that it came with. About 6 months ago, I noticed an intermittent issue where there would be pink lines going down my monitor screen. My monitor is a 10-year old Gateway 17" CRT. The issue with the pink lines went away on its own after a week or so. Last night, I swapped out 2 sticks of 256MB PC2700 with 2 sticks of 512MB PC 3200 memory. When I hooked everything back up, the lines returned, worse than ever. All of the memory is supported and being recognized. I know that the issue should not be connected to installing new memory, but the coincidence is kind of strange. I'm wondering if my vid card is going kaput, or if its the connection with my monitor (one of the tightening pegs on the connector is gone). Anyone have any thoughts?

First check every connection by removing each plug and replacing it, also remove and replace the graphics card.
Are these lines vertical or horizontal, solid or can you see the display underneath?
Vertical lines may indeed indicate the card as being at fault and my include small dots of other colours forming either squares or rectangles, which would indicate a memory fault on the card.
Horizontal lines might indicate the monitor is on its way out and could also include distorted or fuzzy images: Classic signs that the CRT tube is failing.

They are pink (sometimes blue) vertical "distortion" lines. I can still make out the display underneath. I think my plan of attack will be as follows. First connect the monitor to another computer, just to rule it out. Then I'll pull the video card and clean the area with some compressed air and reseat it. If that doesn't do it, I'll run the memory stress test while looking at options for a replacement vid card. Thx for the input!