Noob: suspension question

Hi guys,

I'm planning to change my Lexus  ES300 '02 wheels to 19"s. Haven't got the rims, though. :p 

Will there be a problem, If I use lowering springs without changing my shock absorber? Because some friends of mine said thats fine while others said I could "break" the shock as I compressed the springs. I don't know, so could you guys who know about this give me a clue for that. People suggest me to go with coil over, but I don't have such an easy grand to spend. so, yeah.

Thanks in advance, anyway!