DSA vs RSA

[Carlos Colombo]

Hi all,
I am new to this list and I have same questions.
I hope somebody can answer. If there is a faq where I can gain this
knowledge, please direct me to it.

I am working on project wich will involve exchange of electronic documents.
The requeriment is to ensure that the identity and the contens of electronic
signed messages can not be forged with out the recipient noticing it. Most
users will be using Windows workstations and there will be a unix server.

I have same questions regarding GnuPG and electronic signatures:

I have heard about lots of efforts being made to break RSA-encripted
messages. From this I understand that 1024-bit RSA is safe now will almost
sure be safe for at least 20 years.

I understand that GnuPG uses DSA (Digital Signature Standard) instead of RSA
to sign the documents.
Is it as safe as RSA ? 
Has there been any important efforts to break this algoritm ? 

Another question, perhaps related to the above:
What are the similitudes between RSA and DSA? Are they comparable,
different, essentialy the same...?

 inally:
I am worried about the interoperability between GnuPG and other PGP
programs. Every PGP program supports DSA?

thanks in advance,

Carlos Colombo
+54 (11) 43201485
Buenos Aires, Argentina