Yep, I discovered it's only 802.11g
The new Router helped, but one day I may opt for an adapter.
Then that is what is limiting your download speeds on that laptop. As I mentioned before, 20 Mbps is about the practical limit of 802.11g. If you want faster download speeds on that laptop, then you will need a new WiFi adapter that supports at least 802.11n if not 802.11ac (again, it will also depend on what your router supports as well).
Whether you need faster downloads is another question. If you only use the laptop to do typical web browsing, checking emails, and maybe an occasional file download, then you likely will not notice much from improving your download speeds. The amount that you download when doing typical browsing or email is very small, so you generally don't notice much of a difference between 20 Mbps and 100 Mbps. Even with video streaming, you will not likely notice a difference on the laptop. You can stream well to one device with just something like 5 Mbps. You tend to want/need increase your overall Internet throughput (aka "speed") for video streaming if you have multiple devices that will be streaming at the same time. The main area were you would notice a faster download speed on your laptop while using the Internet would potentially be when downloading large files, but even then the bottleneck that slowing things down may not be your download speed on the laptop, but rather the download speed you achieve from the specific web server you are connected to. The only definite area of benefit for a faster WiFi connection speed would be if you transfer files from the laptop to other computers or devices (say NAS devices) on your local network.