The only idea I've is to check the Joysticktype setting in your configuration file ("DOSBox 0.73 Preferences").

i've tried all available settings. dosbox does see joystick in winxp run on virtual machine on the mac, joysticktype=auto

what is your dosbox version and where have you got it from?
what are your PC specifications?
what games have problems?
post content of "DOSBox Status Window"
enclose your dosbox's config file

following dosbox status for mac and winxp on mac
Attached are mac and winxp config file
It identifies joystick before any games played. I am using joystick for Dark Forces.

MAC OS 10.6.3 2.16 GHz Intel Core 2 Duo-- DosBox terminal status
2.5 GB 667 MHz DDR@ SDRAM

DOSBox version 0.73
Copyright 2002-2009 DOSBox Team, published under GNU GPL.
---
CONFIG:Loading primary settings from config file /Users/myname/Library/Preferences/DOSBox 0.73 Preferences
2010-04-17 13:26:06.907 DOSBox[1058:903] Warning once: This application, or a library it uses, is using NSQuickDrawView, which has been deprecated. Apps should cease use of QuickDraw and move to Quartz.
MIDI:Opened device:coreaudio

This is WinXP Pro on VMFusion virtual machine on above MAC DosBox terminal status

DOSBox version 0.73
Copyright 2002-2009 DOSBox Team, published under GNU GPL.
---
CONFIG:Loading primary settings from config file C:\Documents and Settings\Admin
istrator\Local Settings\Application Data\DOSBox\dosbox-0.73.conf
MIDI:Opened device:win32
One joystick reported, initializing with 4axis
Using joystick 2-axis, 4-button joystick w/view finder, rudder with 3 axes, 4 b
uttons and 1 hat(s)