Possibble Keys (=> send_keys):

LBUTTON
RBUTTON
CANCEL
MBUTTON
BACK
TAB
CLEAR
EINGABE,		EINGABETASTE,		RETURN
UMSCHALT,		SHIFT
STRG,			CONTROL
ALT,			MENU
PAUSE
CAPITAL
KANA
HANGUEL
HANGUL
JUNJA
FINAL
HANJA
KANJI
ESCAPE
CONVERT
NONCONVERT
ACCEPT
MODECHANGE
SPACE
BILD-NACH-OBEN,		PRIOR
BILD-NACH-UNTEN,	NEXT
ENDE,			END
POS1,			HOME
NACH-LINKS,		LEFT
NACH-OBEN,		UP
NACH-RECHTS,		RIGHT
NACH-UNTEN,		DOWN
SELECT
PRINT
EXECUTE
SNAPSHOT
EINFG,			INSERT
ENTF,			DELETE
HELP
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
LWIN
RWIN
APPS
SLEEP
NUMPAD0
NUMPAD1
NUMPAD2
NUMPAD3
NUMPAD4
NUMPAD5
NUMPAD6
NUMPAD7
NUMPAD8
NUMPAD9
MULTIPLY
ADD
SEPARATOR
SUBTRACT
DECIMAL
DIVIDE
F1
F2
F3
F4
F5
F6
F7
F8
F9
F10
F11
F12
F13
F14
F15
F16
F17
F18
F19
F20
F21
F22
F23
F24
NUMLOCK
SCROLL
LUMSCHALT,		LSHIFT
RUMSCHALT,		RSHIFT
LSTRG,			LCONTROL
RSTRG,			RCONTROL
LALT,			LMENU
RALT,			RMENU
ATTN
CRSEL
EXSEL
EREOF
PLAY
ZOOM
NONAME
PA1
OEM_CLEAR

Only 2000/XP:
XBUTTON1
XBUTTON2
BROWSER_BACK
BROWSER_FORWARD
BROWSER_REFRESH
BROWSER_STOP
BROWSER_SEARCH
BROWSER_FAVORITES
BROWSER_HOME
VOLUME_MUTE
VOLUME_DOWN
VOLUME_UP
MEDIA_NEXT_TRACK
MEDIA_PREV_TRACK
MEDIA_STOP
MEDIA_PLAY_PAUSE
LAUNCH_MAIL
LAUNCH_MEDIA_SELECT
LAUNCH_APP1
LAUNCH_APP2