Hmmm, In all honesty, a G4 powerbook is creme of the crop right now, with or without the 17" flatscreen, this thing is a monster and its out for your wallet so try a second hand ( if you can find one ). Pc wise I would scope out the Toshiba Satellite, the P25 model for instance looks like an equivalent to a G4 ( 17" screen, 3,4 GHz ) but is cheaper than a G4 ( $2099 @ 3,2 GHz and super multi drive DVD burner (± formats) w/DVD-RAM (works like an optical HDD) / $2799 for a 3,4 Ghz without the multi, but with 128MB Geforce Go5700 instead ). I would still expand on memory though since it only comes with 512MB, taking new technology in account demanding ( certainly audio ) you'll need more more more more memory.
http://www.toshibadirect.com/td/b2c/cmod.to?seg=PSE&coid=-26379&sel=0&rcid=-26367&ccid=1291021
Fairly cheaper but not directly my first choice ( hey you're spending hella money anyway ) is the Dell Inspiron XPS. With 1GB/400MHz memory it'll go for $2749 or $2399( $72 a month ) with 512MB. Put an extra grand on it and you have the 3.4GHz Extreme Edition boosting more performance(2MB L3 Cache, 0 L3 on non regular 3.4, funny though since the Extreme is fixated at 90nm thickness whilst the regular 3.4 has an oxide thickness of 0.13 micron which is smaller ).
Audio solutions so far I know at the moment are these;
RME Cardbus interface ( Hammerfall DSP on PCMCIA card ). You can use this for internal audio processing, there's a 1394 connection ( not for Fireire ) to connect to the I/O boxes. You wouldn't need it for a pc only daw, but if you have hardware around I suggest getting into the Multiface which offers 8 chnls of I/O @ 24bit/96kHz/105db SNR, digital 1x ADAT ( +sync ) 1x I/O s/pdif - 1x 16chnls midi, 720 chnls internal mixing ( 0latency ). Then there's digiface which is an extended version of the HDSP 9652, meaning only digital I/O; 3 x adat I/O ( + sync ), s/pdif - 2 x 16chnls midi ( high speed ) and 1456 chnls internal mixing. It has two analogue outputs for ya headpiece and monitors ( aux ). The third option is the RME RPM which is aimed at dj's, digital 2 chnl ( stereo, 4 mono ) live performance. It features 5 inputs ( low-noise turntable inputs (Cinch/RCA) with integrated RIAA frequency correction/switchable to Line inputs and a single quadmic preamp ( class A )), 2 stereo out (1 pair balanced, 1 pair unbalanced probably switchable aswell and aux out ) and a 1x 16chnl midi I/O.
These three devices can be hooked to the Cardbus ( and the PCIcard! ), you can also hook up RME Pre amps ( 4 chnl half 19" and 8 chnl 19" ) and other utilities making the RME protocol pretty much a modulair one.
So, in the budget/small hiphop setup the RPM should be sufficient enough, the multiface the most capable one.
The Cardbus comes for $299 and the RPM at $549, no bundle.
The HDSP Multiface/Cardbus (PCMCIA Type II) bundle @ $908
TheHDSP Digiface, and Cardbus (PCMCIA Type II) @ $795
www.rme-audio.com
Echo has made a serie of PCMCIA devices, pretty cheap too but also very basic, not to compare with the RME products ( except for Layla24 maybe ).
Indigo @ $129, 1 stereo out @ 24bit/96kHz, that's it.
Indigo DJ @ $179, 2 stereo out @ 24bit/96kHz.
Indigo I/O @ $179, 1 stereo out, 1 stereo in @ 24bit/96kHz.
A bit more serious
Layla24 8x I/O ( balanced ), 24bit/96kHz - 110dB snr, ADAT pipeline, opt/coax s/pdif, 16chnl midi I/O ( midi in , out and thru ! ). All this is racked in a 1u 19" rack. Comes for $450.
_____
Something else, instead of cardbus you can look at the USB/Firewire cards which opens a whole new catalogue of products but arent ( practicly seen ) portable which I assume is key since we're talking laptops. But anyway....
Firewire
Digi 002 rack ( portable ), nuff said I guess, I/O = 8 analog (with 4 mic preamps), 8 ADAT optical, and 2 S/PDIF. Comes for $1199.
Edirol FA101 ( breakout box ) I/O = 8 analog 24-bit/96kHz, 2 out ( mastertrack ) 24bit/192kHz @ $498.
Egosys Quatafire ( 1/3 of rack ) I/O = 4 analog 24bit/192kHz, 2x micpre ( phantom ), 2 coax spdif I/O, 2x midi I/O @ $399.
MOTU 828MKII ( rack ) I/O= 20 in / 22 out @ 24bit/96kHz ( 10 analog I/O, 1 ADAT, Spdif I/O ) and midi ofcourse. This is a beast and works standalone too ( no pc ), so practicle for mobile efforts. Comes for $750. ( for $1250 there's the 896HD with 8 mic pre's and 24bit/96kHz support )
Im not gonna bother with Metric Halo, very nice but for more info just ask, these babies start @ $999 for a 2chnl preamp ( with nice AD/DA cv but still expensive ).
USB?!?!?
all crap, too slow or desktop biased. If it's not neccesarly needed to be portable, I wouldn't mind going into it, but I guess it's not ( why need a laptop then ? ).