Resizing Partition

Your u could use either of :

1) PartitionMagic
2) resize2fs
3) qtparted (http://qtparted.sourceforge.net/) - A open source PartitionMagic "clone".(Check this out..really works well :-) http://qtparted.sourcreenshot-002-a.jpg)

If you have already resized your partition, all you need to do is
resize your file system. resize2fs will do the job.