Filesystems, LVM, RAID

Right now I have an older Athlon XP system with just one hard drive though I will soon get a desktop with 2 SATA drives. Would using RAID be benefitial? I don’t know much about RAID.
I’m also considering whether to use a LVM partition setup or just regular Ext3 partitions. Will LVM affect performance negatively? I’ve been searching for anything on this to decide whether to use LVM or not. It does have the benefit of resizing partitions.
I read some fs topics and it seems to me that Ext3 has the best balance of performance and stability. I heard that Reiserfs is good for smaller files while Ext3 is good with larger files. Am I correct? Any other recommendations?