Ну а чем тебе собственно семёрка не нравится. ХР как-бы устаревшая и скоро не будет обслуживаться. Ну в общем если решил ставить, то естественно при желании можно снести семёрку, а если позволяет комп можно на другом диске установить и ХР. Будет две оси и соответственно при запуске БИОС постоянно надо будет выставлять с чего грузиться поскольку будет две ОС. Ну а поверх семёрки ставить ХР не получится. Вообще при установке новой Винды на диске где уже есть установленная, старую надо естественно ликвидировать форматированием. Ну как-то так. Может кто ещё варианты подскажет, или меня поправит.

Fixed a major issue with library versioning

Я бы не стал ставить бета версию. Ведь есть же финальные версии.

Now supports NtCreateThreadEx method on 64-bit allowing you to Inject & Remove DLL across Sessions

Added AES decryption of input PDFs. The 'owner' password is still required when decrypting any PDF.
Added merging of bookmarks/outlines when merging full PDFs.
Added new rotate operation, which is a convenient way of rotating select pages of a single PDF.
Added new dump_data_annots operation. Currently it reports only link annotation information.
Added new need_appearances output option. Use this when filling a form with non-ASCII text to ensure the best presentation in Adobe Reader/Acrobat. It won't work when combined with the flatten option.
Improved the compress option so that output PDFs are more compact and efficient.
Added page media information to dump_data output: page rotation, page media bounds and page crop bounds.
Improved the performance of dump_data so it works better with very large PDFs.
Improved the memory management in the Windows binary. This fixes the rare "Too many heap sections" error.
Fixed a bug where form fields with multiple values were not being properly reported by dump_data_fields.
Fixed a burst bug that was corrupting the output PDF pages.
Fixed an input bug to allow interactive prompting of both the user and owner passwords.
Fixed a burst bug so that doc_data.txt is now output to the same directory as the PDF's pages when an output directory is given.
Fixed a bug where indirect references to the PDF ID in the trailer would cause a crash.
Added a test to fill_form so it checks that an input PDF is a form before trying to fill it with data.
Added a return value of 3 for warnings 'PDF information not added' or 'PDF form not filled.'
Improved the error message for cat page range errors.
Fixed the error report when an input page number is out of range.
Fixed a burst bug where document metadata wasn't being copied properly to the output PDFs.
Updated the Bouncy Castle library to 1.48.
When using the cat operation, the output PDF version number is now set to the maximum PDF version of all of the input PDFs. If any of the input PDFs have PDF extension levels, then the greatest extension level is also copied to the output PDF.