[nsp] IOS/boot image compatibility

[Mark]

Hi all!

                 I have an easy question. I´ve got a Cisco 7204 running IOS 12.3(1a)B. The boot image is: KBOOT-M Version 12.2(4) BW. Is it fine or should I upgrade the boot image? If so, which one should I choose and where in the Cisco web page could I find it? The router seems to be running fine although we are having a service performance problem and I would like to be sure it is not our router´s problem (It could be our service provider).
Thanks in advance!!

Regards

Mark