Hello frnds

Please suggest me a suitable UPS. I use C2D proccy with max of 3 SATA drives. 1 Laser printer and 1 external ADSL Modem. is 500 VA UPS sufficient? Is it necessary for a UPS.Any other alternative like surge protector?

I already have APC Home Appliance & Lighting UPS 800VA, 230V at my Home. Can it be used as
a UPS for my entry-level Destop PC. I have also laserPrinter and External Modem.All combined draw 210 Watts. My question is Can UPS meant for Home Appliance & lighting can be used for PC without buying a seperate new UPS for my PC? In the manual of the UPS it is written it can SMPS Loads.Is not PC load a SMPS Load? if it can be used will it give enough time for shutting my PC down? plz help me as iam Assembling a new PC