Various Issues

ok, i've been using Vista Ultimate 64-bit and have a few issues:

1) RAM - i don't know if its a program or application problem, but according
to a game trial, i do not have enough memory (with not even 256MB) for it to
function properly, which i think is impossible, cause a 64-bit OS would HAVE
to run on 4GB of ram.

2) Sleep mode - every time i wake my computer up from sleep mode, it would
only run properly for around 10-15mins before my screen goes black wit a
little box saying "Cannot detect device" (or something like that). the only
way to fix this problem is to manually restart my computer.

3) Internet Connection - Just general slow loading time as compared to when
i first used my computer. its isnt a LONG wait, but it IS...should i say
abnormal? using 100Mbps.

any solutions would be great! and thanks a lot in advance.