You seem to be asking 2 different questions...the PR ratings of AMD CPUs, & how to wire mod them to unlock or change the multiplier.
Here's a list of all the Athlon XP Palomino, Tbred, Barton, & mobile CPUs:
http://en.wikipedia.org/wiki/List_of_AMD_Athlon_XP_microprocessors
Here's the PR calculator:
http://www.ocinside.de/index_e.html?/html/workshop/p_rating.html
Here's the wire mod site:
http://www.ocinside.de/go_e.html?/html/workshop/pinmod/amd_pinmod.html
Asus A7N8X-X
1800+ @ 8 x 210MHz
512MB PC3200
Asus Ti4200 128MB
WinME/WinXP Pro