本人Red Hat Enterprise Linux Server5.5系统，安装VirtualBox如下：
1、下载VirtualBox
地址：http://www.virtualbox.org/wiki/Linux_Downloads，
下载到应的VirtualBox版本: VirtualBox-4.0-4.0.4_70112_rhel5-1.i386.rpm
2、安装gcc
安装顺序如下：
rpm -ivh kernel-headers-2.6.18-164.el5.i386.rpm
rpm -ivh compat-glibc-headers-2.3.4-2.26.i386.rpm
rpm -ivh compat-glibc-2.3.4-2.26.i386.rpm
rpm -ivh compat-libstdc++-33-3.2.3-61.i386.rpm
rpm -ivh compat-libf2c-34-3.4.6-4.i386.rpm
rpm -ivh compat-libgcc-296-2.96-138.i386.rpm
rpm -ivh cpp-4.1.2-46.el5.i386.rpm
rpm -ivh glibc-headers-2.5-42.i386.rpm
rpm -ivh glibc-devel-2.5-42.i386.rpm
rpm -ivh libgomp-4.4.0-6.el5.i386.rpm
rpm -ivh libstdc++-devel-4.1.2-46.el5.i386.rpm
rpm -ivh gcc-4.1.2-46.el5.i386.rpm
rpm -ivh compat-gcc-34-3.4.6-4.i386.rpm
rpm -ivh compat-gcc-34-c++-3.4.6-4.i386.rpm
(Linux系统安装盘里都有)
3、安装kernel
确定系统已经安装如下软件包，缺少的则补上
kernel-2.6.18-194.el5.i686.rpm
kernel-debug-2.6.18-194.el5.i686.rpm
kernel-debug-devel-2.6.18-194.el5.i686.rpm
kernel-devel-2.6.18-194.el5.i686.rpm
kernel-doc-2.6.18-194.el5.noarch.rpm
kernel-headers-2.6.18-194.el5.i386.rpm
kernel-PAE-2.6.18-194.el5.i686.rpm
kernel-PAE-devel-2.6.18-194.el5.i686.rpm
kernel-xen-2.6.18-194.el5.i686.rpm
kernel-xen-devel-2.6.18-194.el5.i686.rpm
4、安装DKMS
从网络上下载DKMS，对应的版本为dkms-2.0.17.5-1.noarch.rpm，或高点版本。
rpm -ivh --test dkms-2.0.17.5-1.noarch.rpm
rpm -ivh dkms-2.0.17.5-1.noarch.rpm
5、安装VirtualBox
执行命令：
rpm -ivh --force VirtualBox-4.0-4.0.4_70112_rhel5-1.i386.rpm
(因为先前kernel和dkms相关软件包不全，安装失败)
执行情况如下：
[root@******** download]# rpm -ivh --force --test VirtualBox-4.0-4.0.4_70112_rhel5-1.i386.rpm
warning: VirtualBox-4.0-4.0.4_70112_rhel5-1.i386.rpm: Header V4 DSA signature: NOKEY, key ID 98ab5139
Preparing... ########################################### [100%]
[root@******** download]# rpm -ivh --force VirtualBox-4.0-4.0.4_70112_rhel5-1.i386.rpm
warning: VirtualBox-4.0-4.0.4_70112_rhel5-1.i386.rpm: Header V4 DSA signature: NOKEY, key ID 98ab5139
Preparing... ########################################### [100%]
1:VirtualBox-4.0 ########################################### [100%]
Creating group 'vboxusers'. VM users must be member of that group!
No precompiled module for this kernel found -- trying to build one. Messages
emitted during module compilation will be logged to /var/log/vbox-install.log.
Stopping VirtualBox kernel modules [确定]
Uninstalling old VirtualBox DKMS kernel modules [确定]
Trying to register the VirtualBox kernel modules using DKMS [确定]
Starting VirtualBox kernel modules [确定]
[root@******** download]#
6、使用VirtualBox
略
其他
1、安装NTFS
RHEL默认只识别win下的vfat，不识别ntfs格式的。如果想要在linux中挂载nffs格式的硬盘方法如下：
(1)下载源码包： http://tuxera.com/opensource/ntfs-3g-2010.10.2.tgz
(2)安装:
tar -zxf ntfs-3g-2010.10.2.tgz
cd ntfs-3g-2010.10.2
./configure
make && make install
(3)安装成功，手动挂载ntfs格式硬盘：
mount -t ntfs-3g /dev/sdb1 /mnt/windows
mount.ntfs-3g /dev/sdb1 /mnt/windows
(4)开机自动挂载ntfs格式硬盘：
/dev/sdb1 /mnt/windows ntfs-3g defaults 0 0