Is there an easy way to repartition my hard disk?

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http://askubuntu.com – I partitioned my hard drive with two separate partitions for Windows and Ubuntu. Now I want to repartition my hard-drive and I'm not really sure on how to do it. I found some programs and tools to handle the partitions but not any info on whether it's possible to merge the two seperated partitions again. Is there a way? (HowTos)