No, to write to a CD, you need to use specialized software, not just a simple copy.
Plus what about copying to replaced a files already on the CD ? I believe you need to clear it first then rewrite everything back. CD are about as inconvenient as a media can get.
The biggest impact would be to max out the memory. That will not help with browsers like Firefox, but will help with other items.
Plus there is a whole world out there that many people ignore or do not know about, USENET and IRC. Accessing those will work with just about any Thinkpad, no matter how old. Plus there is toot for Mastodon (I need to get that working), but not sure if there is a text utility to access lemmy
I have a Thinkpad which is a bit newer then yours (R51e) with OpenBSD on it. I get by quite well with dillo, links (need to try links2), mutt, tin (USENET) and irssi (IRC). All I did is maxed out memory to 2G. But, I never do banking on the Internet. All I do is need to do is get my pdf bank statement once a month which I use a newer Thinkpad for.