mdrew... check pmbuko's post up above for the RAM (viewing the forums flat... wish they'd just kill off that threaded view ;-)
I do think reinstalling windows IS a good idea, if you feel comfortable doing that. Back in the Win9x days that would absolutely be a requirement, these days with XP its not so bad but if a lot of programs got installed on the laptop it definitely would help some by doing that. You really still need to get that RAM upgrade, I suggest do that first and if it doesn't seem to help as much as you hope then perhaps look into formating and reinstalling.
Also, some antivirus programs can really put a strain on a computer, esp again if you don't have a lot of RAM. Usually its not so bad if your CPU is over the 1Ghz mark (which yours is... I think the Athlon 1600 is around 1.3 to 1.4Ghz IIRC).
