I do a lot of mid to low level graphics & video production so I spent my money on RAM, a decent graphics card & a beautiful monitor. I play only 90k-120k hands/mnth cash on PokerStars with only my own hands [no datamined nonsense for me]. I have an all-time history DB for archival purposes & an active playing database. The playing DB is always never more then 7 months of HHs. So at the end of each month I simply create a new DB & import the HH for only the previous 6 months & delete the old active DB. So my DB is never bigger than 500,000 hands & the HUD is very snappy. I don't use autorate or multipanels or note caddy. For notes I use the system in the PokerStars client rather than HM2 because my needs are simple.
All the s/ware I use doesn't benefit from multicores, but does benefit from as much memory as possible. So I do fine with a Win 7 64-bit + 8Gb + dual Intel Core i5 + HDD
If that's you or you play less than me then your $500 system is over-speced
I went with a specialist because I went into a couple of High Street "box shops" & got told obvious B.S.
These people treated me very well online & there must be an equivalent in your region:- Chillblast - UK's Most Awarded Custom Gaming PC Builder
I just bought a basic box with drivers & OS completely up-to-date & bought peripherals from the cheapest source. The refurb for $100 isn't a good deal - there's a scam somewhere... the fans will be rubbish etc - trouble waiting to happen sir