My latency fluctuates a lot when I play CS 1.6 on Windows 7. It used to work fine on Windows XP but ever since I have go this new laptop with Windows 7 the latency goes haywire. One second it is 80 and then it goes to 150 then goes back to 70 then 240 then 85 then 134 and sometimes 400+. I don't know if this is internet problem but I suspect it has something to do with Windows 7 or may be Core i3 processor?
I remember a few years back on dual processor AMD machine I was having similar problem and it turned out the problem was they both were trying to run the game hence the lag or that jerky motion. So I used some command and it was fixed.
May be it is similar problem? But I checked in task manager that only one of the core is running the game. May be some background service is running which is causing this? Search on internet about it but didn't find any solution.