IV = Filename XOR CipherKey?
I am using chunks of 1MB and give them a GUID as filename


That is fine although unnecessary, the entire input file can be encrypted.


  These chunks are then first compresses using DEFLATE to minimize attacks based on known Content


VERY BAD idea, since you are breaking the input file into pieces, you are now exposing the entropy of specific file sections to an attacker. Either compress the file before you break it up, or do not break it up at all (or do not compress it)


  These chunks are then encrypted using Rijndael and a given Cipherkey. The IV will be created as an XOR of my Filename and the Key.


VERY BAD idea, now the attacker has the key. Use a random IV for CBC mode or a sequential IV for CTR mode. You have not specified your mode of operation.


  All chunks are then collected in an XML File, which is saved the same way but named as the original file name


I would keep the actual file name in the XML file in an encrypted format so you do not expose the potential file type or content. You can also keep hashes of the encrypted data, and integrity information in the XML file.


  Are there are other obvious weak spots that I am missing


Probably; your proposed IV generation scheme means you do not know enough about cryptography to be developing an encryption program, do more research and get more education on the subject before continuing. Cryptography Engineering would be a good starting point.