I have ADSL, up to now my only choice in this city in Thailand - not Bangkok) and I pay about $40/month for an advertised 5mb/ps download , but in ACTUALITY, get 2.8 mb/ps. I have a chance to get a fiber optic connection for half that amount - 4mb/ps, but in actuality,I get 2.7mb/ps. I can also upgrade with fiber optic to 10mb/ps with an actual speed of 8.87mb/ps for $6 more/month.
Will the difference in transmissions make a difference in the quality, smoothness of video and audio? For example, with my ADSL, I connect to Slingbox with a not-very-sharp picture and a staccato sound stream. Will upgrading to 10mb/ps make a noticeable difference?

My PC specs:
Toshiba Satellite L505D, with Windows 7 Home Premium, AMD Athlon II Dual Core M300, 3GB Ram, 320 HDD
Anything over 2Mbps should give very good quality. You may have some other issue that is causing the roughness you mention.IF you are USING Slingbox, the extra speed should help. I'm guessing the Slingbox is in a different country, and there is no telling how many connection it goes through before getting to you.

I'd check your speed often just in case it's a physical PROBLEM with your ISP.