Since I have installed froyo my available memory has gone down to 30-40 mb. When I was running 2.1 I usually had 70+ MB free. Most of my apps or larger ones are on my sd card.
It really doesn't matter so don't fret. Look at this on your system and you will have an idea of how it is performing:
Well if you want to dynamically control memory you could always download MinFree. It is a free app and allows you to tweak memory settings to try and get it to where you think they should be. That doesn't necessarily mean the phone will work right but you can tweak away.