hard disk drive(hdd) and memory upgrade on lenovo sl500

[fire_works1234]

i want to upgrade my laptop sl500

1)hdd  

2)memory

to maximum limit my laptop can support and retains its life.

My current pc specs are

HDD:I ran hdd quick test utility and found following details

         WD 160 gb 5400 rpm,cache size:8mb

         Supported Standards: ATA8-ACS, ATA/ATAPI-7, ATA/ATAPI-6, ATA/ATAPI-5

         I dont know its interface i.e whether it is SATA or IDE

Memory: 1 GB  (DDR2-667 DDR2 SDRAM)

BIOS version:1.28

OS:Windows 7 ultimate

Chipset:Mobile intel@GM45 chipset

My query is mainly with hdd that which

1)interface:IDE or Sata 3gb/s or 6gb/s

2)cache size:8mb or 16mb or 32mb

3)maximum capacity size:500gb or 640 gb or 750gb or 1tb

4)rpm: 5400 or 7200

will be best for my laptop 

[boooggy]

hdd can be upgraded to biggest and faster u can find.

the interface is sata2.

i also upgraded first to 160gb 7200rpm and then to 250gb 7200rpm.

after this upgrades ....bought a ssd......best upgrade ever!

as for memory i know that it supports max 4gb (even if i read over the net that it will go  up 2 8gb.....but didnt try it).