That doesnt really sound like a Pine issue to me, running modern DEs with applications like Firefox/Office/.... just easily requires more than 512MB RAM... a Firefox with a few tabs open for example quickly needs a couple hundred MB .... there are some lightweight window managers for X and lightweight browser and office applications but I guess you will have more fun if you find something for your Pine that doesnt require a full graphical UI...
Come have a chat in the Pine IRC channel >>