What could be causing a hard start?

[clk]

I have a 97 328i that is having hard cold starts that seem to be getting worse. Recently the check engine light went on as well. The dealer service dept told me I need a new catalytic converter. Before I lay down a grand plus on a new cat, is there anything else that might be causing this? Also, if it is the cat, any suggestions on replacement? I'm ok with a tool kit but certainly no mechanic. Can I tackle this myself? Any feedback is appreciated.

 

[bimmerfixer]

CLK... I have the same problem with the CE light coming on. Codes that popped in the ECU are for converter efficiency on both banks. After using a full bottle of Sea Foam (sucked through the tailpipe vacuum hose!), the code has gone away when filling up with mid-grade petrol. Wow! What a smoker! Went away after a while of course.
Ok, I recommend you try the Sea Foam first and make sure your using good quality petrol above 89 octane. NO CHEAP STUFF. Then, pull your spark plugs and check for signs of ignition problems (misfires, oil, damage, etc). If the code still pesters you like a furry little chipmunk on caffeine, replace the O2 sensors. You still haven't put your repairs over a grand. As for me...I get better performance, gas mileage and no pesky amber eye staring back at me! Hope that helps!