Quote - Is there any benefit in setting  fixed Virtual Memory using XPs max recommended settting?

Setting a fixed size pagefile (unless overtly large) can only potentially cause you issues.

Windows uses the pagefile to store unbacked memory pages. These are pages that exists nowhere other than in memory, e.g. changes that have been made to a file.

If you set a fixed size and begin to reach that limit then the memory manager is limited in what it can do. It can't page out unbacked store since the pagefile is full, therefore it has to drop memory pages relating to code that is backed on the disk, i.e. program .exe, .dll code etc. e.g. that large document that you have sitting idle in the background that has been changed but hasn't been saved has to be kept in memory since there is no room to page it out to the pagefile. As a result, the performance of other things begin to suffer. When you next need that application code, as part of the application you are running, it has to be paged back in again at the expense of other memory pages that must likewise be dropped in order to keep that document that you haven't saved in memory. Performance suffers because you have limited what the memory manager can do.

If you allow the pagefile to be system managed then the pagefile can be extended - you still get paging but the memory manager can best organise this according to what it thinks you still need and what you don't any more.

Quote - Slower hard drives will benefit by having the MAX set so that the virtual space is initialized at startup and not have to work at growing/shrinking the size during use.

Windows sets a sensible initial fixed size even if set at system managed, it doesn't keep dynamically changing the pagefile size. It'll work within this fixed size until it requires more. If system managed as opposed to manually set, it can add further extents as required.