But before the last checkpoint (=exactly what is stored in bootstrap.dat), signature checking is disabled anyway (and this hasn't changed in 0.
.
.
Do I feel victim to a misunderstanding or do you just have told me a trick? 
I simply should concatenate my current block chain (3 files) into 1 huge file (almost 4.9 GB), name this "bootstrap.dat" and 0.7.* will load this without signature-checking into the bitcoin-client if I start it (and of course build a new blkindex.dat)?
smtp
You perhaps won't succeed with a file > 4GB. There were some limits with fseek or such as far as I remember.
Dia