please help problems with computer

This computer was not acting properly about 1 month ago and dell tech walked me thru a quick wipe and reload of the os and hard drive. Total time for this was about 45 minutes. Am i better off with a total debug/fdisk/format/reinstall. Mouse acts up at times i sometomes get fatal exceptions bsod telling me my computer is busy or unstable. Occasional lockups. I went to pcpitstop.com and they are telling me i have unusually low disk performance drive c. My drive c has an uncached speed of 2.61 and for similiar systaems it should be 3.5mb. It further says it could be due to the disk driver,disk interface,physical disk itself. I am not running an a/v program. Should i have dell walk me thru a complete reinstall or what. Please anyone that can help. Pent 3 4100 800 meg 128 ram 32mbnvidia ddr gforce 2 card windows 98se 20 gig.