In the good old days of the old Republic machines doubled their speed yearly. My three-year-old 2GHz laptop is getting slow, so checked the new machines. To my surprise, the low-end is almost the same. Something fundamental has changed while I didn't look.
This post is being written on AMD Athlon 2600+, and here they sell AMD Athlon 3000+. For the first time in my life, a memory upgrade may be enough to transform and old machine into a modern one.
Eclipse takes 100MB, Firefox takes another 100MB and the app I run on Tomcat takes 100MB. And then you should compile. Not something that fits to 500MB.