Conflicts XP V Vista V Win 7

I'm not sure this is posted correctly, if not please advise.
I have a Toshiba Satellite Pro with XP Pro 5.1.2600 SP3 X86 O S +I E 8+ O E
6 + MS Money 2000 Std. Ver 8.0 all working smoothly! I am about to buy a
second machine, smaller,lighter and with longer batt.working time for travel
use. I am very concerned to avoid conflicts between the XP Pro and more
modern O S's. I intend to use 'Briefcase' or a similar alternative system to
co-ordinate with the Toshiba home base unit. I am being offered smaller
laptops with XP. Vista and Win 7, O S systems and I am concerned that XP
will not be MS supported some time in the not too distant future. All
comments would be appreciated.
Bob

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Bob (R.Longyear)