Is there possibly something slowing down my internet?

I just had virgin media optical 10mb broadband installed today, before I had Tiscali 2mb broadband, and it usually ran slower than 1mb. Anyone now virgin media is installed i went onto speedtest.net and it said I'm getting like 8mb connection which should be about 15mins for an 800mb file, well I thought I'd test this by downloading a 400mb file and its taken roughly 30mins to download so I'm obviously not getting thos speeds, whats the problem?

BTW im testing this on my laptop, right next to the router. I also quickly tried to load a few youtube vids, and they loaded quick enough but it would be loading just after the part it plays so I couldn't skip forward unless I waited for it all to load. I just have a feeling that this isn't 8mb broadband.

 

I'm currently on the same 10MB, depending on the time of day, there are download 'limits' and if you go over this limit, your connect is capped to 75% of the speed, i.e. 2.5MB.

you should be getting something like in my siggy below 'normally'.
Download speeds will also be affected by the actual server you are downloading from, for example, if you try download itunes right now you will get a nice high speed of 700kbps upto 1mbps.
Amount of people on same service in your area will also affect speeds as it is shared at some contention ratio like 50 customers : 1 line? (unsure about this part)

edit: optical as in CABLE service right?

 

Yeah I've downloaded a few different things now and the speeds seem to be about right, I think the line might have been a bit busy. On the speed test it ranged from about just over 6MB to 9+MB in the last two hours. So I'm thinking the speeds are about right. Well thanks anyway.