If you mean the ALL of the PC software directly, and not some web based client and...
If I understand what you're after - you want to remotely access your PC at home from another PC not at home?
If so - there are a half-dozen ways to do this.
I use a free solution called VNC.
Certain versions of Windows have "Remote Desktop Client".
There are commercial packages, logmein.com to name but one...
But - yeah - you pretty much have to have your target PC on all the time.
(You could get tricky with some Wake-On-Lan stuff - but I just leave mine on...)
If you're a LONNG way from your home PC, don't forget a battery backup or something like that.
Nothing hurts more that realizing your home PC just shutdown and needs a button pressed when you're 3000 miles away.
>>Warning Editorial Comment Follows<< Which is why I hate Windoz for a "server" based OS...