Is combination of 1+4 GB memory fine?

"The Lenovo 3000 N200 has two memory slots.

Each memory slot can hold DDR2 PC2-6400 or DDR2 PC2-5300 with a maximum of 2 GB per slot.

So, you will only waste your money on a 4 GB chip.

More information from crucial.com"

2 x 2GB will run in dual-channel mode, and it will be slightly faster. So if most of your use is the time, you have less than 4GB of RAM used, the 2x2GB of RAM will be a better option. On the other hand, if you frequently max out 4GB of RAM, the 4+1GB may be a better option. IIRC, some motherboards require RAM to run in dual-channel mode, so you might want to check with your manufacturer.