Win7 requires at least 6GB of RAM to run efficiently and I recommend 8GB minimum. Win8 is about the same and Win10 will require more. These are all 64-bit systems BTW. Yeah, Win7 will run in 2GB (but nothing else useful will run at any reasonable speed) or 4GB (maybe one program -- NOT Chrome -- will run). The problem is that most new software is underpinned by the same bloatware programming model that plagues Windows and other Microsoft programs: .NET programming.
For example, when Chrome first came out I had a Pentium system running 32-bit WinXP on 3.5GB of RAM. I could open a dozen Chrome windows, each with 10-12 tabs active; all at the same time!!
Fast forward to Chrome ver. in the late-20's. Slower and slower and slower. Finally, around Chrome ver. 34, I noticed that once Chrome got more than 2-3 windows open (maybe 10 tabs altogether), it ran through available RAM and started using the hard drive for memory. As any tech can tell you, the hard drive is the worst substitute this side of Cuneiform Tablets for "RAM" memory substitution (aka, paging). And, slower than molasses at the Arctic Circle in January (not to mention all the damage it's doing to the hard drive - hard drive life is measured in hours of operation generally).
All that to say, hope your present RAM is at 6GB or more, and your motherboard can be upgraded to an i7 processor (which will be needed to get any reasonable performance out of Win10 or Win11). Yeah I know they're selling Pentium Dual-Core and i3 and i5 systems with Win10 ... and performance-wise they're dogs for the most part, offered just to hit a price point the average user and afford up front (tho they pay the price in wasted time and so forth later).
Also take note of Koala's note about GWX.exe. Microsoft _IS_ sneaking through their backdoors into certain Win7 systems and trying to "upgrade" them to Win10 when the owners are not looking. There are marketing and political reasons for this that are not germane to this discussion but it is happening so be on the alert. I read one fellow deleted GWX and it magically reappeared during the next Win7 update. Sneaky they are, Bill's minions. ^_^