recently, when i start my system(ubuntu 7.10) it waits too long at
"Starting common unix printing system(cupsd)" and then i guess it timesout but...the system finally starts which again takes a long time after login to display the desktop....even after that the system is slow throughout....it takes minutes for any application to start...i played arnd with my network settings a lot....thats the only reason i kud guess... help!!

One of the first things to check is to see if there is some process that is hogging most or all of the CPU time. From the command line you can type top. while there are options and commands to make it do other things, by default it will list the processes using the most CPU time in decreasing order. I am sure there is a graphical app in Ubuntu that does the same thing but off hand I am not sure what it is. (I am sure an Internet search would quickly turn up the answer.)

Another thing to check is to see if you are doing excessive swapping. The command line app vmstat will display the swap rate along with other info. See its man page for details.