2144MB is actually available. So your not out of memory.
Computers can run slow when they run too hot. I would check into system temperatures using speedfan or another tool to see if your system is running hot and as a means of avoiding melt down it might be thermal throttling which kills performance as the CPU will be driven lightly to avoid creating excess heat since there is a problem getting rid of heat.
Windows should have had added to it a thermal throttling warning to warn people that their computers are running too warm and so the system is throttling to protect itself which impacts performance. But they dont unless a 3rd party program or you monitor and look for throttling with other tools.
If the CPU is running over 70C then its likely throttling. To correct for this you need to remove dust, or add a cooling pad, or have new thermal compound installed, or new heatsink if heatsink failed, or new cooling fan if its not spinning to 100% speed causing reduced airflow.
http://www.almico.com/sfdownload.phpAlso guessing you meant you have a 1TB hard drive vs 1GB in your description
Here is a video showing how to check for thermal throttling with a tool AIDA64 Extreme
https://www.youtube.com/watch?v=6fY33oFBY_w