i'm no expert at this either, but i have done some messing around with my phone. when you root, you can take off all the apps that sprint loaded on ur phone that you can't remove without root, such as nascar, sprint tv, sprint nav, bejewled demo, etc. alll that bloatware can bog down ur phone.
there are several vids that show you how to root but i found this to be the most helpful one:
http://androidforums.com/samsung-mo...t-2-1-rooting-video-walkthrough-tutorial.html
i know you said you have 2.1 but a reflash can't hurt. this vid will also show you how to put on one of joey's recoveries which is really nice because you can go into recovery and flash things directly from there, such as custom roms, custom themes, etc. and you can also back up ur system/data, which comes in handy if you messed around with ur phone and something goes wrong. you can always just reapply the backup and have ur phone back to where it was.
and if you use the sdx kitchen (that link you put up), adding one of the custom kernals (i really like littlejth's kernal) puts on numus' battery code, which is much better and more accurate than the one on ur phone right now.
some things you can try without rooting is, do a factory reset, which will wiipe ur data, but most of the time is worth it. and try using a task killer. some ppl swear it does nothing, but i swear it helps. i used advanced task killer, and whenever i open it to kill running apps, i also kill the app itself, and it seems to give me really good battery life. also dl spare parts, which allows you to see the battery percentage, as well as check up on what is using the most power off your battery. and if you go through the battery thread, there are tons of tips. hoep that helps