I currently have 4gbs running with my computer it lags rarely but sense i built it, there shouldn't be any, should i add another 2gbs would it stop any lagging. OO and just to add my computer is currently disassembled so i can't really TRY anything, thanks. IMHO 4Gb should be well good ENOUGH. 

Any lag would I think be more likely due to some ''bottlenecking'' in the system, unless your RAM itself has any problems.  Someone else may recall the method for a RAM test - it escapes me right now.Vista, as any other 32bit system, can't even use 4GB of RAM. All you can use is ~3GB.Oops - THX Broni - forgetfull me again!  alright cool ill just keep the 4gb, i read up on it yea UR right 64bit uses 4gb 32bit uses like 2.9 3.1, so how can i fix or indicate bottleneckingRe bottlenecking - I think just run thru all your processes and see if anything stands out as being a problem. 

services.msc will be useful to peek at for what is running.  And even processes in taskmgr.exe can maybe help too re load on RAM etc.With 64bit system, max RAM depends on Windows version:
Theoretically even on a Cray Research Supercomputer there is bottlenecking....what makes you think you have an issue ? ?
How does the machine run ? ?