So I Iike fighting games, alot. The way they play, how their whole system works. Mortal Kombat, Tekken, Soul Cal, and finally Street Fighter. Man I love Street Fighter, especially when I get my ass kicked all day long online.  
Why do I suck and why do I still love the game ? This love/hate relationship is ridiculous. I traded in Street Fighter 4, telling myself I'd never ever touch it again. But then I watch that really long GB QL of SSF 4 and I feel this urge in my gut that maybe I wasn't getting something, like how to do Ultra Combos (as I said, I sucked). So I give in to my primal urges and buy the game. And you'll never guess, I suck hard. I can't beat arcade mode on easy and despite trainig Sakura out her ass, good luck seeing an Ultra from me in the heat of battle. This doesn't happen in MK or any other game. I feel like I can't get the moves out quick enough in SF (yes i play with a controller) and its just the most frustrating that I love. 
So if you want me to boost your bp, I challenge YOU sir online ! 

Have you hit the trial mode yet? I've found I learnt most of my SF4 skills from doing the first few trials to get to know everyone, watch videos of pro-level SF and then just play alot of endless matches vs one or two opponents.
 
I play stick now, I couldn't imagine playing on a controller any good anymore, but I know several Bombers who play on a controller.
Have you tried playing stick? 
 
You should hit the PS3 Community Thread and see if you can get some games with the regulars. SF is definitely a game you get better at the more you play.

... you can't do an ultra? By controller, do you mean your using a guitar controller? because that would make it hard.

I used to be exactly like you when it comes to Street Fighter.  Horrible at fighting games but loving them to much to quit all together.  I played vanilla for a few months and then moved on to the newest hottest thing.  I almost passed on SSFIV but on release day I, almost sub-consciously, walked right into a Wal-mart and grabbed a copy before they were even on shelves.  I got it home and realized I had bought the game I said I wouldn't, heh.  I have Stockholm Syndrome for this game and nothing I do can rip me away from it.
 
Now, with over 600 matches under my belt the hardest setting in arcade mode is a joke and I'm going 50/50 with Ryu, Balrog, and Bison in ranked.  Some say you can't develop reaction time and pure timing skills but I'm living proof that it can happen. None of this means I'm very good but I can and do improve every time I play. If you don't have good timing or reaction then characters like Bison and Balrog are amazing when it comes to playing mind games.  
 
Whats your XBLA tag and I'll add you and we can go a few rounds.  I play mostly on Thurs and Fridays.

practice the moves very slowly in training mode, then try them a little faster etc, and then go play people. youll lose a lot, but thats how it goes.

you can also try to slow down a bit when trying to pull those ultras. its easy to miss inputs when you mash as fast as possible, especially on a pad. but the most important thing is you are still having fun and that's what its all about.

Sakura isn't a good starting character either, you should try out Ryu and all other more conventional shotos.

You on Xbox or PS3?  
If you're on Xbox 360, send me an PM with Gamertag etc and I'll give you some games. :)

" ... you can't do an ultra? By controller, do you mean your using a guitar controller? because that would make it hard. "

Just practice, you'll get better eventually :) 
 
And if you're playing in the PS3, don't use the joystick, use the D-Pad.  And Street Fighter games has always been about sliding your thumb quickly enough to make the move, not just pressing the directions (for thumb warriors of course...).  Play a lot of endless matches with friends and you'll get a lot better eventually. 
 
I also agree that Sakura is not really a beginner-friendly character.  If you want to use shoto-characters, choose Ryu or Ken.  If non-shoto characters, go for Juri or Cammy I guess. :)

The main allure of Street Fighter is that it's easy to play and hard to master.  I love the game, and since I've got my arcade stick I've been practicing trying to get better, so I've been in your shoes trying to re-learn the game on a stick.  Check out this guy's tutorials  
http://www.youtube.com/user/VesperArcade.  They've greatly improved my game, you can also go on the SRK forums and check out specific characters once you get the hang of the game.  Also if you play online and get completely blasted, try watching your own replays with the Commands on and you'll see exactly what you're doing during that match and what they're doing too.  Other than that, practice makes perfect.  Good luck and have fun with it, even tho you lose.