After you defrag try putting ice on the top of the box too, could be temerature related.
Alternately it could be that you're BELOW the recomended system requirements for RAM when running EQ on XP.
Pentium® III or greater
512 MB RAM
32 MB Direct3D compliant video card and hardware T&L (i.e. ATI Radeon or Nvidia GeForce 2 or greater)
DirectX 8.0 compatible sound card
56.6k (or faster) Internet connection
16X speed CD-ROM
1.5 GB+ hard drive space
I'd buy another 256 RAM stick. Unless you're using XP for EQ and word processing only you're going to se performance hits from the lack of RAM in nearly everything.
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