The difference from say 192 to 256 of course is not that great, but you are sitting at the lower limit before you start swapping to your HD, which definately will affect performance. My rig started with 128mb and the jump from 128 to 384 was a substantial difference(probably similar to going from 128-256 actually)in performance in everyday computing(noticed no difference at all going from 384mb to 640mb), but I do video editing and graphics work as well and at times still swap during editing, but adding the extra 256 made a big difference with large files.
With the price of ram and you say you multitask office applications, it certainly wouldn't be a waste, but maybe not a big difference as well.
I also use Startup Control Panel to configure my Applications that load at startup(great BTW) and your long bootup is maybe from Win2k looking for your network.