The SSD group at Micron has done extensive research into the behavior of Windows XP and Windows Vista under different conditions.  To gather data, the SATA interface was analyzed and data captured while installing, booting, shutting down, and running Office productivity applications on both operating systems.

The results of this research show that XP and Vista do indeed handle their interfaces to an SSD differently. The main difference is XP does not align the data in the best way for an SSD.  Vista, on the other hand, does align the data.  These findings differ from other claims we’ve seen that Vista is somehow worse for an SSD.  In fact Vista is better for an SSD (incidentally, so is Windows Mojave). The example below illustrates the difference… By aligning the data and not partially filling NAND pages, performance is optimized for the SSD.

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Another key difference between Vista and XP is that Vista enables background drive defragmentation by default. Defragmentation is totally unnecessary with an SSD and actually wears the drive out more rapidly. However, most OEMs will disable background defrag on systems that ship with SSDs and Vista.  So—if you happen to be buying a new SSD for the holidays, be sure defrag is off when you upgrade.  You don’t want to hold performance back by making your new SSD live in the HDD days-of-old.