How aggressively have you done your data modelling?

>One of my clients has a huge table that I've split four times so that DBF and FPT sizes are about equal and each physical file is less than 2GB. But, I'm approaching that limit yet again - it doesn't make sense any more to keep splitting that table.
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>The high price of SQL Server has my client gagging (this is only 1 of his >300 tables but the only one with the problem). So, I've briefly looked at open source DBs and played with Firebird (old Interbase). It has a huge file size limit but, unfortunately, on Win32 machines the OS limit of 2GB still holds.
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>Can anyone recommend any open source DBs that can work on Win32 machines with > 2GB tables?
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>What other DBs would you suggest?
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>Has anyone tried any other DBs on 64-bit XP machines?