Should I install Vista Business ?

Why not compare the versions of Vista for yourself and see which features you need (link below). If you plan to authenticate to a domain server (Active Directory), Vista Business is what you are going to want. If you are going to work with local accounts on the laptop, just go with one of the Vista home editions. XP Pro is still a viable option and given you only have 1 GB of RAM it is the better choice. For Vista, bump it to 2GB or higher for it to run decent.