The higher the refresh rate the better viewing you get but it makes your monitor work harder, it CAN reduce the life of your monitor, especially if you play fast an loose outside the recommended maximums of your monitor.
Think of playing with the refresh rates as overclocking your monitor, the higher you go the better performance but do so at your own risk. My personal preference is >=80
AMD Athlon 64 3000+ (Overclocked to 3300+)
1GB PC3200 DDR
2x200GB Seagate SATA RAID 0
BFG 6800GT OC w\\128MB Ram
2x 19\" Samsung 930B LCDs