Regarding computer: Building your own computer will always leads to cheapest and most powerful machine, I recommend going with liquid cooling. My computer is nearly silent even after 3 or 4 years of owning it now. The nice thing about building your own, you can pick out exactly what kind of case you want and what not, and whenever you decide you want to upgrade a part, you just take out an old one and put in the new one, or if you want to have two ssds, you just add it on, but you would want a bigger case so there is room for all of that. What I did back in the day when I was less educated about this stuff is just paid a site to put it together for me, I just picked out all of the parts I wanted, which is fine because it saved me some time but now if I was to do it all over again I would put it together myself. Lots of videos on how to do that on youtube.
Internet: Often times you can fix your internet problems by simply restarting the router. The next step to improve your internet speed which I'm guessing you haven't done is setting the DNS to OpenDNS. In simple terms it just basically means how your machine communicates with the internet. It's quite easy to do. Start>control panel>network and internet>network connections. Right click on your network connection whatever it's called>properties. Click on internet protocol version 4 (TCP /IPv4) click properties. Switch obtain DNS server address automatically to Use the following addresses and type in those numbers. It should look like this: http://gyazo.com/0463ae80d982fecd4690349886d8979d
You can use 208.67.222.222 and 208.67.220.220, or 8.8.8.8 and 8.8.4.4. or what I have. I haven't done any research on which ones are the best. This will make your internet faster.
Win 8 vs Win 7: lots of articles on this on google. I want to troll you but I won't :). Basically even my super nerdy friend that works with computers quite a lot said that as soon as he got his laptop he updated
from Win 8 to 7 and that Win 7 is just much better. I can ask him why if you really want me to but I didn't bother.