For some reason setting the Terminal window bounds is very buggy. I resorted to using the deprecated methods {position and size} and have to loop it three times to ensure that it positions correctly.
I tied this to command-; in my app launcher, QuickSilver
tell application "Finder"
--make new Finder window
activate
if not (exists window index 1) then
make new Finder window
end if
set {x1, y1, x2, y2} to bounds of window index 1
end tell
tell application "Terminal"
activate
if (count of windows) is 0 then
tell application "Terminal" to activate
tell application "System Events" to tell process "Terminal" to keystroke "t" using command down
end if
-- For some reason it can take up to 3 times for Terminal to be properly adjusted
set L to {1, 2, 3}
repeat with xxx in L
set {xx1, yy1, xx2, yy2} to bounds of window index 1
set position of window index 1 to {x1, y1 + {yy2 - yy1}}
set size of window index 1 to {x2 - x1, y2 - y1}
end repeat
end tell