There are plenty of people mentioning Win7 64 it in here.
Stutters can occur in any sim for a million reasons unfortunately. For example a slow HD access on new areas loading etc. Apart from graphics settings - updating sound card drivers, defrag, faster HD, faster vid/CPU, minimising background tasks, disable AV if offline etc can help.
What name are you searching for the folder? I installed in Win7 with no problem and I see the folder and data fine.
Win7 (and Vista) have a habit of moving data for apps to different folders. "ProgramData" is one.
Also it locks down read/write to those areas not great for some programs.
I have Win7 64 and that can't write a file from a graphics package randomly to a folder, permission issue, then I click save and it saves it. Think that's a Win7 bug.