I am being stupid I know I am

but what is optimised Seti
Not stupid. It took me 4 years to become aware of it.
The standard seti application is designed to run on as wide a range of CPUs as possible. So it's reliable but not fast.
If you know how you can customise the app for a particular CPU. It then will do the same amount of work much more efficiently so your credit per day will rise.
The splendid fellow who has done this is called
Crunch3r and this is where you can download the optimised Seti applications.
The particular file you want for your 3800+ running 32 bit vista is called AK V8 Windows x32 SSE3 and you will be able to
download it from this link.
Once you've dowloaded & unzipped it, just follow the instructions which say:
Installation of the optimized app is simple.
1)Stop BOINC service by "net stop boinc" command or exit from BOINC Manager if you're running it in single-user mode
2) Copy all files in the "Files to install" directory to your BOINC\projects\setiathome.berkeley.edu folder.
There is a file called "app_info.xml" included that will make BOINC use this app automatically.
3) Restart BOINC service by "net start boinc" or reopen BOINC Manager if you're running it in single-user mode.
That's it, you're done! You can open your task manager to see that it's really the new optimized app crunching your WUs.
BOINC will tell you that it found app_info.xml and is using an "anonymous platform".
Good luck!