That should be able to run a newer version of Linux than the knoppix you have. Looks like it came with 512mb RAM from the factory so that would need to be increased to run any newer OS.
https://support.hp.com/us-en/document/c00683794
Maximum is 1gb 2x for a total of 2gb which still isn’t great. You’ll want a lightweight Linux. Just do a web search for lightweight linux 32 bit. There aren’t many that will run on a 32 bit system these days. XP isn’t even safe to surf with anymore. Major target for malware and as you say, it won’t run up to date browsers.
Not sure about connecting to xfinity. You’ll have to take that up with them. Is there xfinity software of some sort installed on the machine? Do you or did you ever have to log into xfinity via a browser?
3.3GHz is pretty good but you really ought to think about finding a 64 bit machine. 32 bit is just getting obsolete.
I had one last thought about this thread. I agree with Pollard that 2GB max is a very limited line.
But if you wanted to force the issue it wouldn’t probably be too hard. The LXDE desktop uses next to nothing in terms of system memory and resources and XFCE is equally pretty light weight. That would leave a lot of memory left for one of the lesser-used browsers.
https://ubuntulearn.com/best-lightweight-web-browsers-for-linux-in-2020/