need some xbox 360 help

so, i've had a ps2 for several years now, and, well, it's time to get an upgrade. i was, at first, planning to get the ps3, but it's damned expensive even with the price slashes if i also want backwards compatibility. i have always been a fan of halo, so i'm venturing for the first time into the xbox community...i am aware that HD-DVD has lost to Blu-Ray, but i am not a big movie or TV watcher, so i don't think i'll need a very big hard drive for the 360 (or care that it plays HD-DVD. so, i've had my eye on this xbox bundle
basically, this set includes
* Xbox 360 Pro console
* 20GB detachable hard drive
* Wireless controller
* Xbox Live headset
* High-definition AV cable
* Ethernet cable
* Detachable faceplate
* Xbox Live Silver membership
* HDMI port
* Forza 2 game
* Marvel Alliance game
i do not plan to watch movies, but i am planning to play some of the old xbox games, and i believe i need a hard drive for that. what i'm asking is:
do i need any extra accessories? (i plan to subscribe to Xbox live and play online).
how do i be as cost effective as possible? (e.g. are there better sets than this..are buying the system and accessories separately a better deal? etc.)
will the xbox lag on my TV? it is a standard definition TV.
basically, this set includes
* Xbox 360 Pro console
* 20GB detachable hard drive
* Wireless controller
* Xbox Live headset
* High-definition AV cable
* Ethernet cable
* Detachable faceplate
* Xbox Live Silver membership
* HDMI port
* Forza 2 game
* Marvel Alliance game
i do not plan to watch movies, but i am planning to play some of the old xbox games, and i believe i need a hard drive for that. what i'm asking is:
do i need any extra accessories? (i plan to subscribe to Xbox live and play online).
how do i be as cost effective as possible? (e.g. are there better sets than this..are buying the system and accessories separately a better deal? etc.)
will the xbox lag on my TV? it is a standard definition TV.