Why is Chrome appearing to use so much more memory than Task Manager indicates? Why is my pagefile being used when I have around 1.1GB of memory? Can I set Chrome to run in RAM and not in the pagefile? How can 20 tabs use 600MB? That's 30MB per tab.
Your experience is normal. I have 72 tabs open right now (several projects going at once) and Chrome is taking 2.7 GB of virtual memory (2 GB RAM + 700MB pagefile). That is about 37MB per tab (my worst tab takes 170MB). And I have even disabled the Flash plugin -- otherwise it would be a lot higher.
You should look at Chrome's own task manager, by clicking on the "wrench" icon, Tools->Task Manager. This will be a lot more helpful for you than Windows Task Manager since it will clarify which tabs use the most memory.
By the developers' own admission, Chrome uses more memory than single-process browsers when you have multiple tabs open, because certain program data has to be duplicated for each tab. This is because Chrome starts a new process for each new tab (except when you open a link in a new tab, then it seems to share a process with the tab containing the original link).
This has clear benefits for reliability (since one bad tab won't crash your whole browser), security (less likely that one malicious site can compromise other tabs' data), and performance (your current tab gains priority and can perform faster). In exchange you have to give it extra memory.
Multi-process architecture does have a memory advantage over long sessions: it does a better job freeing memory when you close tabs.
This is the future of web browsing. Since most computing takes place on the web now, web browsers need the same multi-process architecture that provides reliability to traditional operating systems like Windows/Mac/Linux. (IE8 added this feature and I expect other browsers will do so. Firefox puts plugins in their own process, and I think different processes for different tabs is in their roadmap.)
Your system doesn't have a lot of RAM. You only have 1GB but modern systems sold today all have at least 2GB, and most have at least 4GB. It would probably be cheap for you to upgrade to 4GB.