I have a HP DV9000 with an Intel G2 SSD as primary drive running Win XP SP2 after making all Microsoft updates and installing the all I programs I use. It is partitioned as 55 GB to XP and 25 GB to Slackware linux.
A couple of comments - I am not running XP with my SSD's but I have at various times (just not now).
Use a benchmark tool presented in these forums to test drives - adding a new tool and asking why its not the same doesnt get us anywhere.
Trim support was added into Windows 7, but Intels SSD toolbox will work under XP. There are a lot of caveats around Trim in Windows 7 so Google for details.
You should have AHCI or SATA selected - if not, it could be your BIOS/system are too old to make full use of them. That will be a huge limiter.
Also, what version of SATA does this system support? Sata 1 limits you to around 150Mbytes/sec
You should use the SSD Toolbox to realign the SSD pages - nothing else you have will do that. Intel suggests once a week.
Tools to improve performance - not much on an SSD. Defrags do not add value, turn off Searching and Indexing, it only slows things down.