I should be normal. Are you running XP or Vista? For vista, my memory usage is always 60+% idle and I have 1GB. If you don't video edit or game then 1GB should be more than enough. If you game or do other memory intensive tasks, then 2GB should be the minimum. RAM is really cheap these days anyway.
In the case of RAM, more is better, but that is if your motherboard can support it and more importantly your hip pocket must support it also.