too many SQL connections opening

hi all

i'm using the 6.28 version with, i believe, the MS SQL (though an .mdb Access file does open and keep info - so is that Access and maybe not MS SQL?) for about 18 months.  the average number of posts in the forum is about 20,000-30,000, which are deleted every month.  there are about 8000 registered users, though the number of actual active users is lower.

recently, the SQL admin of our web hosting notified me that the SQL machine is being exhausted by our forum, as there appear to be either multiple connections to the SQL opening for each user, or that the connections do not close appropriately.

i wanted to know:

1. is this bug known and maybe has a fix, or should i upgrade the forum altogether to the latest version. 

2. if so, are the 6.28 or the 7.8 versions built to handle the usage load i described above?

3. does the MS SQL 7.8 version use caching (my SQL guy told me to ask that)?

thank you,

rany

ok, thanks.  i guess i should upgrade then.

if i want to start using the MS SQL version instead of the Access one, how can i keep my users database (it's an .mdb file)?

What's the file size of the access .mdb?