mudiare

I am looking to upgrade the system in my 98a4. I am not an audiophile, i do not plan on adding amps,subs (maybe an amp) or anything else. I am just looking for a decent attractive looking headunit with an aux input for my ipod and some speakers and tweeters (or components). I just need something that will sound marginally better than stock. I would also like to know how hard it is to upgrade the system (fitment issues and all). Please i am a newbie so bear with me. Thanks you