Internet Crashes Out Since Windows 7 Arrived

my brother recently installed windows 7 on his pc, and since then we have had internet connection issues, but it is ok when you run laptops wirelessly (hope that makes sense!) which are running vista and xp. the network provider (orange) who say everything is fine. although i am not entirely convinced because we have low status and slow connections as soon as soon as it hits about 5.30pm. how do i check if throttling is happening?also, he recently installed a brand new processor and a brand new graphics card put in. it is a nivida geforce gt 220.i am an avid user of secondlife and this constantly crashes out the connection, which is only reconnected after a restart. if i watch or use anything such as Internet, any video or music streaming off any other site, or online gaming that has a high graphic content, the internet connection drops out too, and i get a yellow triangle with an exclamation mark in it. if i run the repair and diagnose thing that comes up - it says there is no issue detected. but clearly there is something wrong. my brother also separated the logins so my brother and i have different passwords. the connection drops on both logins. if i stick to text based internet sites, then it stays connected a whole lot longer. i can go for hours without having to restart. however, if i break into videochat on msn or gmail chat, there is a lot of breakups in sound, and lag in type chat - going into cam chat crashes me out again totally.if i unplug the live box, and replug it - i have to restart the whole system. in fact if i restart the system it connects straight away - unfortunately, if i return to the same stream - a few minutes in, it crashes again. it's driving me crazy!anyone any idea what i can do. i have no idea about computers at all...i have googled but don't get the responses as i am not entirely sure what i am looking for as i am not computer minded.computer spec:dell inspiron 530intel core duo cpu e6750 2.66ghzprocessor: 4gb (2.75gb useable)32bit operating systemwindows 7 orange network, livebox